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First pass at flash driver.

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86
README.md
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@ -2,7 +2,7 @@
These drivers support nonvolatile memory chips and the littlefs filesystem.
Currently supported devices use technologies having superior performance
Currently supported devices include technologies having superior performance
compared to flash. Resultant storage has much higher write endurance. In some
cases read and write access times may be shorter. EEPROM and FRAM chips have
much lower standby current than SD cards, benefiting micropower applications.
@ -26,14 +26,15 @@ The drivers have the following common features:
## 1.2 Technologies
Currently supported technologies are EEPROM and FRAM (ferroelectric RAM). These
are nonvolatile random access storage devices with much higher endurance than
flash memory. Flash has a typical endurance of 10K writes per page. The figures
for EEPROM and FRAM are 1-4M and 10^12 writes respectively. In the case of the
FAT filing system 1M page writes probably corresponds to 1M filesystem writes
because FAT repeatedly updates the allocation tables in the low numbered
sectors. If `littlefs` is used I would expect the endurance to be substantially
better owing to its wear levelling architecture.
Currently supported technologies are Flash, EEPROM and FRAM (ferroelectric
RAM). The latter two are nonvolatile random access storage devices with much
higher endurance than flash memory. Flash has a typical endurance of 10-100K
writes per page. The figures for EEPROM and FRAM are 1-4M and 10^12 writes
respectively. In the case of the FAT filing system 1M page writes probably
corresponds to 1M filesystem writes because FAT repeatedly updates the
allocation tables in the low numbered sectors. Under `littlefs` I would expect
the endurance to be substantially better owing to its wear levelling
architecture.
## 1.3 Supported chips
@ -49,20 +50,23 @@ M95M02-DRMN6TP and M95M02-DWMN3TP/K. The latter has a wider temperature range.
In the table below the Interface column includes page size in bytes.
| Manufacturer | Part | Interface | Bytes | Technology | Docs |
|:------------:|:---------:|:---------:|:------:|:----------:|:-------------------------:|
| STM | M95M02-DR | SPI 256 | 256KiB | EEPROM | [SPI.md](./spi/SPI.md) |
| Microchip | 25xx1024 | SPI 256 | 128KiB | EEPROM | [SPI.md](./spi/SPI.md) |
| Microchip | 24xx512 | I2C 128 | 64KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx256 | I2C 128 | 32KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx128 | I2C 128 | 16KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx64 | I2C 128 | 8KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Adafruit | 1895 | I2C n/a | 32KiB | FRAM | [FRAM.md](./fram/FRAM.md) |
| Manufacturer | Part | Interface | Bytes | Technology | Docs |
|:------------:|:---------:|:---------:|:------:|:----------:|:----------------------------:|
| Cypress | S25FL256L | SPI 4096 | 32MiB | Flash | [FLASH.md](./flash/FLASH.md) |
| Cypress | S25FL128L | SPI 4096 | 16MiB | Flash | [FLASH.md](./flash/FLASH.md) |
| STM | M95M02-DR | SPI 256 | 256KiB | EEPROM | [SPI.md](./spi/SPI.md) |
| Microchip | 25xx1024 | SPI 256 | 128KiB | EEPROM | [SPI.md](./spi/SPI.md) |
| Microchip | 24xx512 | I2C 128 | 64KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx256 | I2C 128 | 32KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx128 | I2C 128 | 16KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Microchip | 24xx64 | I2C 128 | 8KiB | EEPROM | [I2C.md](./i2c/I2C.md) |
| Adafruit | 1895 | I2C n/a | 32KiB | FRAM | [FRAM.md](./fram/FRAM.md) |
Documentation:
[SPI.md](./spi/SPI.md)
[I2C.md](./i2c/I2C.md)
[FRAM.md](./fram/FRAM.md)
[FLASH.md](./flash/FLASH.md)
## 1.4 Performance
@ -78,6 +82,11 @@ The drivers provide the benefit of page writing in a way which is transparent.
If you write a block of data to an arbitrary address, page writes will be used
to minimise total time.
In the case of flash memory page writing is mandatory: a sector is written by
first erasing it, a process which is slow. This physical limitation means that
the driver must buffer an entire 4096 byte sector. This contrasts with FRAM and
EEPROM drivers where the buffering comprises a few bytes.
# 2. Choice of interface
The principal merit of I2C is to minimise pin count. It uses two pins
@ -91,21 +100,38 @@ apparent on reads: write speed is limited by the EEPROM device. In principle
expansion is limited only by the number of available pins. (In practice
electrical limits may also apply).
In the case of the Microchip devices supported, the SPI chip is larger at
128KiB compared to a maximum of 64KiB in the I2C range.
The larger capacity chips generally use SPI.
# 3. Design details and test results
# 3. Design details, littlefs support
The fact that the API enables accessing blocks of data at arbitrary addresses
implies that the handling of page addressing is done in the driver. This
contrasts with drivers intended only for filesystem access. These devolve the
detail of page addressing to the filesystem by specifying the correct page size
in the ioctl and (if necessary) implementing a block erase method.
A key aim of these drivers is support for littlefs. This requires the extended
block device protocol as described
[here](http://docs.micropython.org/en/latest/reference/filesystem.html) and
[in the uos doc](http://docs.micropython.org/en/latest/library/uos.html).
This protocol describes a block structured API capable of handling offsets into
the block. It is therefore necessary for the device driver to deal with any
block structuring inherent in the hardware. The device driver must enable
access to varying amounts of data at arbitrary physical addresses.
The nature of the drivers in this repo implies that the page size in the ioctl
is arbitrary. Littlefs requires a minimum size of 128 bytes -
These drivers achieve this by implementing a device-dependent `readwrite`
method which provides read and write access to arbitrary addresses, with data
volumes which can span page and chip boundaries. A benefit of this is that the
array of chips can be presented as a large byte array. This array is accessible
by Python slice notation: behaviour provided by the hardware-independent base
class.
A consequence of the above is that the page size in the ioctl does not have any
necessary connection with the memory hardware, so the drivers enable the value
to be specified as a constructor argument. Littlefs requires a minimum size of
128 bytes -
[theoretically 104](https://github.com/ARMmbed/littlefs/blob/master/DESIGN.md).
The driver only allows powers of 2. Testing was done with 512 bytes.
The drivers only allow powers of 2: in principle 128 bytes could be used. The
default in MicroPython's littlefs implementation is 512 bytes and all testing
was done with this value. FAT requires 512 bytes minimum: FAT testing was done
with the same block size.
The test programs use littlefs and therefore require MicroPython V1.12 or
later.
later. On platforms that don't support littlefs the options are either to adapt
the test programs for FAT (code is commented out) or to build firmware with
littlefs support. This can be done by passing `MICROPY_VFS_LFS2=1` to the
`make` command.

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bdevice.py
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# bdevice.py Hardware-agnostic base class for block devices.
# bdevice.py Hardware-agnostic base classes.
# BlockDevice Base class for general block devices e.g. EEPROM, FRAM.
# FlashDevice Base class for generic Flash memory (subclass of BlockDevice).
# Released under the MIT License (MIT). See LICENSE.
# Copyright (c) 2019 Peter Hinch
# Hardware-independent class implementing the uos.AbstractBlockDev protocol with
# simple and extended interface. It should therefore support littlefs.
# BlockDevice: hardware-independent class implementing the uos.AbstractBlockDev
# protocol with extended interface. It supports littlefs.
# http://docs.micropython.org/en/latest/reference/filesystem.html#custom-block-devices
# The subclass must implement .readwrite which can read or write arbitrary amounts
@ -76,3 +78,76 @@ class BlockDevice:
if op == 6: # Erase
return 0
# Hardware agnostic base class for flash memory, where a single sector is cached.
# This minimises RAM usage. Under FAT wear is reduced if you cache at least two
# sectors. This driver is primarily intended for littlefs which has no such issue.
# Subclass must provide these hardware-dependent methods:
# .rdchip(addr, mvb) Read from chip into memoryview: data guaranteed not to be cached.
# .flush(cache, addr) Erase physical sector and write out an entire cached sector.
# .readwrite As per base class.
class FlashDevice(BlockDevice):
def __init__(self, nbits, nchips, chip_size, sec_size):
super().__init__(nbits, nchips, chip_size)
self.sec_size = sec_size
self._cache_mask = sec_size - 1 # For 4K sector size: 0xfff
self._fmask = self._cache_mask ^ 0x3fffffff # 4K -> 0x3ffff000
self._cache = bytearray(sec_size) # Cache always contains one sector
self._mvd = memoryview(self._cache)
self._acache = 0 # Address in chip of byte 0 of current cached sector
def read(self, addr, mvb):
nbytes = len(mvb)
next_sec = self._acache + self.sec_size # Start of next sector
if addr >= next_sec or addr + nbytes <= self._acache:
self.rdchip(addr, mvb) # No data is cached: just read from device
else:
# Some of address range is cached
boff = 0 # Offset into buf
if addr < self._acache: # Read data prior to cache from chip
nr = self._acache - addr
self.rdchip(addr, mvb[:nr])
addr = self._acache # Start of cached data
nbytes -= nr
boff += nr
# addr now >= self._acache: read from cache.
sa = addr - self._acache # Offset into cache
nr = min(nbytes, self._acache + self.sec_size - addr) # No of bytes to read from cache
mvb[boff : boff + nr] = self._mvd[sa : sa + nr]
if nbytes - nr: # Get any remaining data from chip
self.rdchip(addr + nr, mvb[boff + nr : ])
return mvb
def synchronise(self):
# print('SYNCHRONISE')
self.flush(self._mvd, self._acache) # Write out old data
# TODO Performance enhancement: if cache intersects address range, update it first.
# Currently in this case it would be written twice.
def write(self, addr, mvb):
nbytes = len(mvb)
acache = self._acache
boff = 0 # Offset into buf.
while nbytes:
if (addr & self._fmask) != acache:
self.synchronise() # Erase sector and write out old data
self._fill_cache(addr) # Cache sector which includes addr
offs = addr & self._cache_mask # Offset into cache
npage = min(nbytes, self.sec_size - offs) # No. of bytes in current sector
self._mvd[offs : offs + npage] = mvb[boff : boff + npage]
nbytes -= npage
boff += npage
addr += npage
return mvb
# Cache the sector which contains a given byte addresss. Save sector
# start address.
def _fill_cache(self, addr):
addr &= self._fmask
self.rdchip(addr, self._mvd)
self._acache = addr
def initialise(self):
self._fill_cache(0)

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flash/FLASH.md 100644
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# 1. A MicroPython Flash memory driver
This driver supports the Cypress S25FL256L and S25FL128L chips, providing 64MiB
and 32MiB respectively. These have 100K cycles of write endurance (compared to
10K for Pyboard Flash memory).
Multiple chips may be used to construct a single logical nonvolatile memory
module. The driver allows the memory either to be mounted in the target
filesystem as a disk device or to be addressed as an array of bytes.
The driver has the following attributes:
1. It supports multiple Flash chips to configure a single array.
2. It is cross-platform.
3. The SPI bus can be shared with other chips.
4. It supports filesystem mounting.
5. Alternatively it can support byte-level access using Python slice syntax.
Flash technology requires a sector buffer. Consequently this driver uses 4KiB
of RAM (compared to minuscule amounts for the FRAM and EEPROM drivers). This is
an inevitable price for the large capacity of flash chips.
FAT and littlefs filesystems are supported but the latter is preferred owing to
its resilience and wear levelling characteristics.
# 2. Connections
Any SPI interface may be used. The table below assumes a Pyboard running SPI(2)
as per the test program. To wire up a single flash chip, connect to a Pyboard
as below. Pin numbers an 8 pin SOIC or WSON package. Inputs marked `nc` may be
connected to 3V3 or left unconnected.
| Flash | Signal | PB | Signal |
|:-----:|:-------:|:---:|:------:|
| 1 | CS | Y5 | SS/ |
| 2 | SO | Y7 | MISO |
| 3 | WP/ | nc | - |
| 4 | Vss | Gnd | Gnd |
| 5 | SI | Y8 | MOSI |
| 6 | SCK | Y6 | SCK |
| 7 | RESET/ | nc | - |
| 8 | Vcc | 3V3 | 3V3 |
For multiple chips a separate CS pin must be assigned to each chip: each one
must be wired to a single chip's CS line. Multiple chips should have 3V3, Gnd,
SCL, MOSI and MISO lines wired in parallel.
If you use a Pyboard D and power the chips from the 3V3 output you will need
to enable the voltage rail by issuing:
```python
machine.Pin.board.EN_3V3.value(1)
```
Other platforms may vary.
## 2.1 SPI Bus
The devices support baudrates up to 50MHz. In practice MicroPython targets do
not support such high rates. In testing I found it necessary to specify 5MHz
otherwise erratic results occurred. This was probably because of my breadboard
test setup. On a PCB I would hope to run at a sunbstantially higher rate. The
SPI bus is fast: wiring should be short and direct.
# 3. Files
1. `flash_spi.py` Device driver.
2. `bdevice.py` (In root directory) Base class for the device driver.
3. `flash_test.py` Test programs for above.
Installation: copy files 1 and 2 (optionally 3) to the target filesystem.
# 4. The device driver
The driver supports mounting the Flash chips as a filesystem. Initially the
device will be unformatted so it is necessary to issue code along these lines
to format the device. Code assumes two devices and also assumes the littlefs
filesystem:
```python
import os
from machine import SPI, Pin
from flash_spi import FLASH
cspins = (Pin(Pin.board.Y5, Pin.OUT, value=1), Pin(Pin.board.Y4, Pin.OUT, value=1))
flash = FLASH(SPI(2, baudrate=20_000_000), cspins)
# Format the filesystem
os.VfsLfs2.mkfs(flash) # Omit this to mount an existing filesystem
os.mount(flash,'/fl_ext')
```
The above will reformat a drive with an existing filesystem: to mount an
existing filesystem simply omit the commented line.
Note that, at the outset, you need to decide whether to use the array as a
mounted filesystem or as a byte array. The filesystem is relatively small but
has high integrity owing to the hardware longevity. Typical use-cases involve
files which are frequently updated. These include files used for storing Python
objects serialised using Pickle/ujson or files holding a btree database.
The SPI bus must be instantiated using the `machine` module.
## 4.1 The FLASH class
An `FLASH` instance represents a logical flash memory: this may consist of
multiple physical devices on a common SPI bus.
### 4.1.1 Constructor
This tests each chip in the list of chip select pins - if a chip is detected on
each chip select line a flash array is instantiated. A `RuntimeError` will be
raised if a device is not detected on a CS line.
Arguments:
1. `spi` Mandatory. An initialised SPI bus created by `machine`.
2. `cspins` A list or tuple of `Pin` instances. Each `Pin` must be initialised
as an output (`Pin.OUT`) and with `value=1` and be created by `machine`.
3. `size=16384` Chip size in KiB. Set to 32768 for the S25FL256L chip.
4. `verbose=True` If `True`, the constructor issues information on the flash
devices it has detected.
5. `sec_size=4096` Chip sector size.
6. `block_size=9` The block size reported to the filesystem. The size in bytes
is `2**block_size` so is 512 bytes by default.
### 4.1.2 Methods providing byte level access
It is possible to read and write individual bytes or arrays of arbitrary size.
Because of the very large size of the supported devices this mode is most
likely to be of use for debugging. When writing in this mode it is necessary to
be aware of the characteristics of flash devices. The memory is structured in
blocks of 4096 bytes. To write a byte a block has to be read into RAM and the
byte changed. The block on chip is erased then the new data written out. This
process is slow (~300ms). In practice writing is deferred until it is necessary
to access a different block: it is therefore faster to write data to
consecutive addresses. Writing individual bytes to random addresses would be
slow and cause undue wear because of the repeated need to erase and write
sectors.
The examples below assume two devices, one with `CS` connected to Pyboard pin
Y4 and the other with `CS` connected to Y5.
#### 4.1.2.1 `__getitem__` and `__setitem__`
These provides single byte or multi-byte access using slice notation. Example
of single byte access:
```python
from machine import SPI, Pin
from flash_spi import FLASH
cspins = (Pin(Pin.board.Y5, Pin.OUT, value=1), Pin(Pin.board.Y4, Pin.OUT, value=1))
flash = FLASH(SPI(2, baudrate=20_000_000), cspins)
flash[2000] = 42
print(flash[2000]) # Return an integer
```
It is also possible to use slice notation to read or write multiple bytes. If
writing, the size of the slice must match the length of the buffer:
```python
from machine import SPI, Pin
from flash_spi import FLASH
cspins = (Pin(Pin.board.Y5, Pin.OUT, value=1), Pin(Pin.board.Y4, Pin.OUT, value=1))
flash = FLASH(SPI(2, baudrate=20_000_000), cspins)
flash[2000:2002] = bytearray((42, 43))
print(flash[2000:2002]) # Returns a bytearray
```
Three argument slices are not supported: a third arg (other than 1) will cause
an exception. One argument slices (`flash[:5]` or `flash[13100:]`) and negative
args are supported. See [section 4.2](./SPI.md#42-byte-addressing-usage-example)
for a typical application.
#### 4.1.2.2 readwrite
This is a byte-level alternative to slice notation. It has the potential
advantage when reading of using a pre-allocated buffer. Arguments:
1. `addr` Starting byte address
2. `buf` A `bytearray` or `bytes` instance containing data to write. In the
read case it must be a (mutable) `bytearray` to hold data read.
3. `read` If `True`, perform a read otherwise write. The size of the buffer
determines the quantity of data read or written. A `RuntimeError` will be
thrown if the read or write extends beyond the end of the physical space.
### 4.1.3 Other methods
#### synchronise
This causes the cached sector to be written to the device. Should be called
prior to power down. **TODO: check flush/synchronise**
#### The len() operator
The size of the flash array in bytes may be retrieved by issuing `len(flash)`
where `flash` is the `FLASH` instance.
#### scan
Activate each chip select in turn checking for a valid device and returns the
number of flash devices detected. A `RuntimeError` will be raised if any CS
pin does not correspond to a valid chip.
Other than for debugging there is no need to call `scan()`: the constructor
will throw a `RuntimeError` if it fails to communicate with and correctly
identify the chip.
#### erase
Erases the entire array. Beware: this takes many minutes.
### 4.1.4 Methods providing the block protocol
These are provided by the base class. For the protocol definition see
[the pyb documentation](http://docs.micropython.org/en/latest/library/uos.html#uos.AbstractBlockDev)
also [here](http://docs.micropython.org/en/latest/reference/filesystem.html#custom-block-devices).
`readblocks()`
`writeblocks()`
`ioctl()`
# 5. Test program flash_spi.py
This assumes a Pyboard 1.x or Pyboard D with two chips wired to SPI(2) as
above with chip selects connected to pins `Y4` and `Y5`. It provides the
following.
## 5.1 test()
This performs a basic test of single and multi-byte access to chip 0. The test
reports how many chips can be accessed. Existing array data will be lost. This
primarily tests the driver: as a hardware test it is not exhaustive.
## 5.2 full_test()
This is a hardware test. Tests the entire array. Fills each 256 byte page with
random data, reads it back, and checks the outcome. Existing array data will be
lost. **TODO long run time.**
## 5.3 fstest(format=False)
If `True` is passed, formats the flash array as a littlefs filesystem and mounts
the device on `/fl_ext`. If no arg is passed it mounts the array and lists the
contents. It also prints the outcome of `uos.statvfs` on the array.
## 5.4 cptest()
Tests copying the source files to the filesystem. The test will fail if the
filesystem was not formatted. Lists the contents of the mountpoint and prints
the outcome of `uos.statvfs`.
## 5.5 File copy
A rudimentary `cp(source, dest)` function is provided as a generic file copy
routine for setup and debugging purposes at the REPL. The first argument is the
full pathname to the source file. The second may be a full path to the
destination file or a directory specifier which must have a trailing '/'. If an
OSError is thrown (e.g. by the source file not existing or the flash becoming
full) it is up to the caller to handle it. For example (assuming the flash is
mounted on /fl_ext):
```python
cp('/flash/main.py','/fl_ext/')
```
See `upysh` in [micropython-lib](https://github.com/micropython/micropython-lib.git)
for other filesystem tools for use at the REPL.

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# flash_spi.py MicroPython driver for Cypress S25FL128L 16MiB and S25FL256L 32MiB
# flash devices.
# Released under the MIT License (MIT). See LICENSE.
# Copyright (c) 2019 Peter Hinch
import time
from micropython import const
from bdevice import FlashDevice
# Supported instruction set:
# 4 byte address commands
_READ = const(0x13)
_PP = const(0x12) # Page program
_SE = const(0x21) # Sector erase
# No address
_WREN = const(6) # Write enable
_RDSR1 = const(5) # Read status register 1
_RDSR2 = const(7) # Read status register 2
_RDID = const(0x9f) # Read manufacturer ID
_CE = const(0xc7) # Chip erase (takes minutes)
_SEC_SIZE = const(4096) # Flash sector size 0x1000
# Logical Flash device comprising one or more physical chips sharing an SPI bus.
class FLASH(FlashDevice):
def __init__(self, spi, cspins, size=16384, verbose=True, sec_size=_SEC_SIZE, block_size=9):
# args: virtual block size in bits, no. of chips, bytes in each chip
if size not in (16384, 32768):
raise ValueError('Valid sizes: 16384 or 32768KiB')
super().__init__(block_size, len(cspins), size * 1024, sec_size)
self._spi = spi
self._cspins = cspins
self._ccs = None # Chip select Pin object for current chip
self._bufp = bytearray(6) # instruction + 4 byte address + 1 byte value
self._mvp = memoryview(self._bufp) # cost-free slicing
self._page_size = 256 # Write uses 256 byte pages.
self.scan(verbose)
self.initialise() # Initially cache sector 0
# **** API SPECIAL METHODS ****
# Scan: read manf ID
def scan(self, verbose):
mvp = self._mvp
for n, cs in enumerate(self._cspins):
mvp[:] = b'\0\0\0\0\0\0'
mvp[0] = _RDID
cs(0)
self._spi.write_readinto(mvp[:4], mvp[:4])
cs(1)
if mvp[1] != 1 or mvp[2] != 0x60 or not (mvp[3] == 0x18 or mvp[3] == 0x19):
raise RuntimeError('Flash not found at cs[{}].'.format(n))
if verbose:
s = '{} chips detected. Total flash size {}MiB.'
print(s.format(n + 1, self._a_bytes // (1024 * 1024)))
return n
# Chip erase. Can take minutes.
def erase(self):
mvp = self._mvp
for cs in self._cspins: # For each chip
mvp[0] = _WREN
cs(0)
self._spi.write(mvp[:1]) # Enable write
cs(1)
mvp[0] = _CE
cs(0)
self._spi.write(mvp[:1]) # Start erase
cs(1)
self._wait_rdy() # Wait for erase to complete
# **** INTERFACE FOR BASE CLASS ****
# Write cache to a sector starting at byte address addr
def flush(self, cache, addr): # cache is memoryview into buffer
self._sector_erase(addr)
mvp = self._mvp
nbytes = self.sec_size
ps = self._page_size
start = 0 # Current offset into cache buffer
while nbytes > 0:
# write one page at a time
self._getaddr(addr, 1)
cs = self._ccs # Current chip select from _getaddr
mvp[0] = _WREN
cs(0)
self._spi.write(mvp[:1]) # Enable write
cs(1)
mvp[0] = _PP
cs(0)
self._spi.write(mvp[:5]) # Start write
self._spi.write(cache[start : start + ps])
cs(1)
self._wait_rdy() # Wait for write to complete
nbytes -= ps
start += ps
addr += ps
# Read from chip into a memoryview. Address range guaranteed not to be cached.
def rdchip(self, addr, mvb):
nbytes = len(mvb)
mvp = self._mvp
start = 0 # Offset into buf.
while nbytes > 0:
npage = self._getaddr(addr, nbytes) # No. of bytes in current chip
cs = self._ccs
mvp[0] = _READ
cs(0)
self._spi.write(mvp[:5])
self._spi.readinto(mvb[start : start + npage])
cs(1)
nbytes -= npage
start += npage
addr += npage
# Read or write multiple bytes at an arbitrary address.
# **** Also part of API ****
def readwrite(self, addr, buf, read):
mvb = memoryview(buf)
self.read(addr, mvb) if read else self.write(addr, mvb)
return buf
# **** INTERNAL METHODS ****
def _wait_rdy(self): # After a write, wait for device to become ready
mvp = self._mvp
cs = self._ccs # Chip is already current
while True:
mvp[0] = _RDSR1
cs(0)
self._spi.write_readinto(mvp[:2], mvp[:2])
cs(1)
if not (mvp[1] & 1):
break
time.sleep_ms(1)
# Given an address, set current chip select and address buffer.
# Return the number of bytes that can be processed in the current chip.
def _getaddr(self, addr, nbytes):
if addr >= self._a_bytes:
raise RuntimeError("Flash Address is out of range")
ca, la = divmod(addr, self._c_bytes) # ca == chip no, la == offset into chip
self._ccs = self._cspins[ca] # Current chip select
mvp = self._mvp
mvp[1] = la >> 24
mvp[2] = la >> 16 & 0xff
mvp[3] = (la >> 8) & 0xff
mvp[4] = la & 0xff
pe = (addr & -self._c_bytes) + self._c_bytes # Byte 0 of next chip
return min(nbytes, pe - la)
# Erase sector. Address is start byte address of sector.
def _sector_erase(self, addr):
self._getaddr(addr, 1)
cs = self._ccs # Current chip select from _getaddr
mvp = self._mvp
mvp[0] = _WREN
cs(0)
self._spi.write(mvp[:1]) # Enable write
cs(1)
mvp[0] = _SE
cs(0)
self._spi.write(mvp[:5]) # Start erase
cs(1)
self._wait_rdy() # Wait for erase to complete

138
flash/flash_test.py 100644
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@ -0,0 +1,138 @@
# flash_test.py MicroPython test program for Cypress SPI Flash devices.
# Released under the MIT License (MIT). See LICENSE.
# Copyright (c) 2019 Peter Hinch
import uos
from machine import SPI, Pin
from flash_spi import FLASH
# Add extra pins if using multiple chips
cspins = (Pin(Pin.board.Y5, Pin.OUT, value=1), Pin(Pin.board.Y4, Pin.OUT, value=1))
# Return an EEPROM array. Adapt for platforms other than Pyboard.
def get_device():
if uos.uname().machine.split(' ')[0][:4] == 'PYBD':
Pin.board.EN_3V3.value(1)
flash = FLASH(SPI(2, baudrate=5_000_000), cspins)
print('Instantiated Flash')
return flash
# Dumb file copy utility to help with managing EEPROM contents at the REPL.
def cp(source, dest):
if dest.endswith('/'): # minimal way to allow
dest = ''.join((dest, source.split('/')[-1])) # cp /sd/file /fl_ext/
with open(source, 'rb') as infile: # Caller should handle any OSError
with open(dest,'wb') as outfile: # e.g file not found
while True:
buf = infile.read(100)
outfile.write(buf)
if len(buf) < 100:
break
# ***** TEST OF DRIVER *****
def _testblock(eep, bs):
d0 = b'this >'
d1 = b'<is the boundary'
d2 = d0 + d1
garbage = b'xxxxxxxxxxxxxxxxxxx'
start = bs - len(d0)
end = start + len(garbage)
eep[start : end] = garbage
res = eep[start : end]
if res != garbage:
return 'Block test fail 1:' + str(list(res))
end = start + len(d0)
eep[start : end] = d0
end = start + len(garbage)
res = eep[start : end]
if res != b'this >xxxxxxxxxxxxx':
return 'Block test fail 2:' + str(list(res))
start = bs
end = bs + len(d1)
eep[start : end] = d1
start = bs - len(d0)
end = start + len(d2)
res = eep[start : end]
if res != d2:
return 'Block test fail 3:' + str(list(res))
def test():
eep = get_device()
sa = 1000
for v in range(256):
eep[sa + v] = v
for v in range(256):
if eep[sa + v] != v:
print('Fail at address {} data {} should be {}'.format(sa + v, eep[sa + v], v))
break
else:
print('Test of byte addressing passed')
data = uos.urandom(30)
sa = 2000
eep[sa:sa + 30] = data
if eep[sa:sa + 30] == data:
print('Test of slice readback passed')
block = 256
res = _testblock(eep, block)
if res is None:
print('Test block boundary {} passed'.format(block))
else:
print('Test block boundary {} fail'.format(block))
print(res)
block = eep._c_bytes
if eep._a_bytes > block:
res = _testblock(eep, block)
if res is None:
print('Test chip boundary {} passed'.format(block))
else:
print('Test chip boundary {} fail'.format(block))
print(res)
else:
print('Test chip boundary skipped: only one chip!')
# ***** TEST OF FILESYSTEM MOUNT *****
def fstest(format=False):
eep = get_device()
# ***** CODE FOR LITTLEFS *****
if format:
uos.VfsLfs2.mkfs(eep)
try:
uos.mount(eep,'/fl_ext')
except OSError: # Already mounted
pass
print('Contents of "/": {}'.format(uos.listdir('/')))
print('Contents of "/fl_ext": {}'.format(uos.listdir('/fl_ext')))
print(uos.statvfs('/fl_ext'))
def cptest():
eep = get_device()
if 'fl_ext' in uos.listdir('/'):
print('Device already mounted.')
else:
try:
uos.mount(eep,'/fl_ext')
except OSError:
print('Fail mounting device. Have you formatted it?')
return
print('Mounted device.')
cp('flash_test.py', '/fl_ext/')
cp('flash_spi.py', '/fl_ext/')
print('Contents of "/fl_ext": {}'.format(uos.listdir('/fl_ext')))
print(uos.statvfs('/fl_ext'))
# ***** TEST OF HARDWARE *****
def full_test():
eep = get_device()
page = 0
for sa in range(0, len(eep), 256):
data = uos.urandom(256)
eep[sa:sa + 256] = data
got = eep[sa:sa + 256]
if got == data:
print('Page {} passed'.format(page))
else:
print('Page {} readback failed.'.format(page))
break
page += 1

6
fram/fram_test.py
Wyświetl plik

@ -38,13 +38,13 @@ def _testblock(eep, bs):
eep[start : end] = garbage
res = eep[start : end]
if res != garbage:
return 'Block test fail 1:' + res
return 'Block test fail 1:' + str(list(res))
end = start + len(d0)
eep[start : end] = d0
end = start + len(garbage)
res = eep[start : end]
if res != b'this >xxxxxxxxxxxxx':
return 'Block test fail 2:' + res
return 'Block test fail 2:' + str(list(res))
start = bs
end = bs + len(d1)
eep[start : end] = d1
@ -52,7 +52,7 @@ def _testblock(eep, bs):
end = start + len(d2)
res = eep[start : end]
if res != d2:
return 'Block test fail 3:' + res
return 'Block test fail 3:' + str(list(res))
def test():
fram = get_fram()

6
i2c/I2C.md
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@ -240,9 +240,9 @@ lost.
## 5.3 fstest(format=False)
If `True` is passed, formats the EEPROM array as a FAT filesystem and mounts
the device on `/eeprom`. If no arg is passed it mounts the array and lists the
contents. It also prints the outcome of `uos.statvfs` on the array.
If `True` is passed, formats the EEPROM array as a littlefs filesystem and
mounts the device on `/eeprom`. If no arg is passed it mounts the array and
lists the contents. It also prints the outcome of `uos.statvfs` on the array.
## 5.4 cptest()

6
i2c/eep_i2c.py
Wyświetl plik

@ -39,13 +39,13 @@ def _testblock(eep, bs):
eep[start : end] = garbage
res = eep[start : end]
if res != garbage:
return 'Block test fail 1:' + res
return 'Block test fail 1:' + str(list(res))
end = start + len(d0)
eep[start : end] = d0
end = start + len(garbage)
res = eep[start : end]
if res != b'this >xxxxxxxxxxxxx':
return 'Block test fail 2:' + res
return 'Block test fail 2:' + str(list(res))
start = bs
end = bs + len(d1)
eep[start : end] = d1
@ -53,7 +53,7 @@ def _testblock(eep, bs):
end = start + len(d2)
res = eep[start : end]
if res != d2:
return 'Block test fail 3:' + res
return 'Block test fail 3:' + str(list(res))
def test():
eep = get_eep()

6
spi/SPI.md
Wyświetl plik

@ -257,9 +257,9 @@ lost.
## 5.3 fstest(format=False, stm=False)
If `True` is passed, formats the EEPROM array as a FAT filesystem and mounts
the device on `/eeprom`. If no arg is passed it mounts the array and lists the
contents. It also prints the outcome of `uos.statvfs` on the array.
If `True` is passed, formats the EEPROM array as a littlefs filesystem and
mounts the device on `/eeprom`. If no arg is passed it mounts the array and
lists the contents. It also prints the outcome of `uos.statvfs` on the array.
## 5.4 cptest(stm=False)

6
spi/eep_spi.py
Wyświetl plik

@ -43,13 +43,13 @@ def _testblock(eep, bs):
eep[start : end] = garbage
res = eep[start : end]
if res != garbage:
return 'Block test fail 1:' + res
return 'Block test fail 1:' + str(list(res))
end = start + len(d0)
eep[start : end] = d0
end = start + len(garbage)
res = eep[start : end]
if res != b'this >xxxxxxxxxxxxx':
return 'Block test fail 2:' + res
return 'Block test fail 2:' + str(list(res))
start = bs
end = bs + len(d1)
eep[start : end] = d1
@ -57,7 +57,7 @@ def _testblock(eep, bs):
end = start + len(d2)
res = eep[start : end]
if res != d2:
return 'Block test fail 3:' + res
return 'Block test fail 3:' + str(list(res))
def test(stm=False):
eep = get_eep(stm)