RP2.spi: Add deinit method, adapt tests to use it.

rp2/RP2.md

@@ -96,6 +96,17 @@ It has been tested at a clock rate of 24MHz on an RP2040 running at 250MHz.
 
 The following files may be found in the `spi` directory:
 * `spi_slave.py` Main module.
+* `tx.py` Transmitter script: provides SPI data for receiver demos below.
+These demos use two linked boards, one supplying data, the other receiving.
+* `rx.py` Demo of nonblocking receiver.
+* `rxb.py` Blocking read demo.
+* `arx.py` Asynchronous read demo.
+Demos are run from the `rp2` directory by issuing (e.g.):
+```python
+>>> import spi.rx
+```
+Tests. These run on a single board and test special cases such as recovery from
+overruns.
 * `slave_sync_test` Test using synchronous code.
 * `slave_async_test` Test using asynchronous code.
 * `master_slave_test.py` Full test of master linked to slave, with the latter
@@ -108,7 +119,7 @@ the following pins should be linked:
 * 1-18 SCK
 * 2-17 CSN
 
-Tests are run by issuing (e.g.):
+Tests are run from the `rp2` directory by issuing (e.g.):
 ```py
 >>> import spi.master_slave_test
 ```
@@ -154,6 +165,8 @@ large enough for the expected message. The method returns immediately. When a
 message arrives and reception is complete, the callback runs. Its integer arg is
 the number of bytes received. If a message is too long to fit the buffer, excess
 bytes are lost.
+* `deinit()` Close the interface. This should be done on exit to avoid hanging
+at the REPL.
 
 The nonblocking `.read_into()` method enables processing to be done while
 awaiting a complete message. The drawback (compared to `.read()`) is that
@@ -213,6 +226,9 @@ phase "ping pong" buffering). Reception is via an asynchronous method
 ```
 As with all asynchronous code, this task pauses while others continue to run.
 
+On application exit `SpiSlave.deinit()` should be called to avoid hanging at the
+REPL.
+
 # 2.6 Operation
 
 The slave will ignore all interface activity until CS/ is driven low. It then

rp2/spi/arx.py

@@ -1,3 +1,7 @@
+# spi.arx.py Demo of asynchronous SPI slave
+
+# Released under the MIT License (MIT). See LICENSE.
+# Copyright (c) 2025 Peter Hinch
 
 import asyncio
 from machine import Pin, reset
@@ -8,14 +12,17 @@ mosi = Pin(0, Pin.IN)
 sck = Pin(1, Pin.IN)
 csn = Pin(2, Pin.IN)
 
+piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
+
+
 async def main():
-    piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
     async for msg in piospi:
         print(f"Received: {len(msg)} bytes:")
         print(bytes(msg))
         print()
 
+
 try:
     asyncio.run(main())
 finally:
-    reset()
+    piospi.deinit()

rp2/spi/master_slave_test.py

@@ -21,7 +21,19 @@ def callback(dma):  # Hard ISR
     tsf.set()  # Flag user code that transfer is complete
 
 
-async def send(cs, spi, data):
+# Sender uses nonblocking master
+cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
+pin_sck = Pin(18, Pin.OUT, value=0)
+pin_mosi = Pin(19, Pin.OUT, value=0)
+spi = SpiMaster(4, 10_000_000, pin_sck, pin_mosi, callback)
+# Pins for slave
+mosi = Pin(0, Pin.IN)
+sck = Pin(1, Pin.IN)
+csn = Pin(2, Pin.IN)
+piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
+
+
+async def send(data):
     cs(0)  # Assert CS/
     spi.write(data)  # "Immediate" return: minimal blocking.
     await tsf.wait()  # Wait for transfer complete (other tasks run)
@@ -38,24 +50,18 @@ async def receive(piospi):
 
 async def test():
     obuf = bytearray(range(512))  # Test data
-    # Master CS/
-    cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
-    # Pins for slave
-    mosi = Pin(0, Pin.IN)
-    sck = Pin(1, Pin.IN)
-    csn = Pin(2, Pin.IN)
-    piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
     rt = asyncio.create_task(receive(piospi))
     await asyncio.sleep_ms(0)  # Ensure receive task is running
-    # Pins for Master
-    pin_sck = Pin(18, Pin.OUT, value=0)
-    pin_mosi = Pin(19, Pin.OUT, value=0)
-    spi = SpiMaster(4, 10_000_000, pin_sck, pin_mosi, callback)
     print("\nBasic test\n")
-    await send(cs, spi, obuf[:256])
-    await send(cs, spi, obuf[:20])
-    await send(cs, spi, b"The quick brown fox jumps over the lazy dog")
+    await send(obuf[:256])
+    await send(obuf[:20])
+    await send(b"The quick brown fox jumps over the lazy dog")
     print("\nDone")
 
 
-asyncio.run(test())
+try:
+    asyncio.run(test())
+finally:
+    piospi.deinit()
+    spi.deinit()
+    asyncio.new_event_loop()

rp2/spi/rx.py

@@ -1,3 +1,8 @@
+# spi.rx.py Demo of nonblocking SPI reception
+
+# Released under the MIT License (MIT). See LICENSE.
+# Copyright (c) 2025 Peter Hinch
+
 from machine import Pin, reset
 from .spi_slave import SpiSlave
 from time import sleep_ms
@@ -32,4 +37,4 @@ def test():
 try:
     test()
 finally:
-    reset()
+    piospi.deinit()

rp2/spi/rxb.py

@@ -0,0 +1,24 @@
+# spi.rxb.py Demo of SPI slave blocking read.
+
+# Released under the MIT License (MIT). See LICENSE.
+# Copyright (c) 2025 Peter Hinch
+
+from machine import Pin, reset
+from .spi_slave import SpiSlave
+
+mosi = Pin(0, Pin.IN)
+sck = Pin(1, Pin.IN)
+csn = Pin(2, Pin.IN)
+
+piospi = SpiSlave(bytearray(300), sm_num=4, mosi=mosi, sck=sck, csn=csn)
+
+
+def test():
+    while True:
+        print(bytes(piospi.read()))  # Message received. Process it.
+
+
+try:
+    test()
+finally:
+    piospi.deinit()

rp2/spi/slave_async_test.py

@@ -12,8 +12,21 @@ from machine import Pin, SPI
 import asyncio
 from .spi_slave import SpiSlave
 
+# Pins for Master
+cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
+pin_miso = Pin(16, Pin.IN)  # Not used: keep driver happy
+pin_sck = Pin(18, Pin.OUT, value=0)
+pin_mosi = Pin(19, Pin.OUT, value=0)
+spi = SPI(0, baudrate=10_000_000, sck=pin_sck, mosi=pin_mosi, miso=pin_miso)
 
-async def send(cs, spi, obuf):
+# Pins for slave
+mosi = Pin(0, Pin.IN)
+sck = Pin(1, Pin.IN)
+csn = Pin(2, Pin.IN)
+piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
+
+
+async def send(obuf):
     cs(0)
     spi.write(obuf)
     cs(1)
@@ -36,38 +49,30 @@ async def get_msg(piospi):
 
 async def test():
     obuf = bytearray(range(512))  # Test data
-    # Master CS/
-    cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
-    # Pins for slave
-    mosi = Pin(0, Pin.IN)
-    sck = Pin(1, Pin.IN)
-    csn = Pin(2, Pin.IN)
-    piospi = SpiSlave(buf=bytearray(300), sm_num=0, mosi=mosi, sck=sck, csn=csn)
     rt = asyncio.create_task(receive(piospi))
     await asyncio.sleep_ms(0)  # Ensure receive task is running
-    # Pins for Master
-    pin_miso = Pin(16, Pin.IN)  # Not used: keep driver happy
-    pin_sck = Pin(18, Pin.OUT, value=0)
-    pin_mosi = Pin(19, Pin.OUT, value=0)
-    spi = SPI(0, baudrate=10_000_000, sck=pin_sck, mosi=pin_mosi, miso=pin_miso)
     print(spi)
     print("\nBasic test\n")
-    await send(cs, spi, obuf[:256])
-    await send(cs, spi, obuf[:20])
+    await send(obuf[:256])
+    await send(obuf[:20])
     print("\nOverrun test: send 512 bytes, rx buffer is 300 bytes.\n")
-    await send(cs, spi, obuf)
+    await send(obuf)
     print("\nTest subsequent transfers\n")
-    await send(cs, spi, b"The quick brown fox jumps over the lazy dog")
-    await send(cs, spi, b"A short message")
-    await send(cs, spi, b"A longer message")
+    await send(b"The quick brown fox jumps over the lazy dog")
+    await send(b"A short message")
+    await send(b"A longer message")
     rt.cancel()  # Terminate the read task
     await asyncio.sleep_ms(0)
     print("\nAsynchronous read into user supplied buffer\n")
     asyncio.create_task(get_msg(piospi))  # Set up for a single read
     await asyncio.sleep_ms(0)  # Ensure above task gets to run
-    await send(cs, spi, b"Received by .as_read_into()")
+    await send(b"Received by .as_read_into()")
     await asyncio.sleep_ms(100)
     print("\nDone")
 
 
-asyncio.run(test())
+try:
+    asyncio.run(test())
+finally:
+    piospi.deinit()
+    asyncio.new_event_loop()

rp2/spi/slave_sync_test.py

@@ -12,53 +12,59 @@ from machine import Pin, SPI, SoftSPI
 from .spi_slave import SpiSlave
 from time import sleep_ms
 
+# Create synchronous master using standard library
+cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
+pin_miso = Pin(16, Pin.IN)  # Not used: keep driver happy
+pin_sck = Pin(18, Pin.OUT, value=0)
+pin_mosi = Pin(19, Pin.OUT, value=0)
+spi = SPI(0, baudrate=10_000_000, sck=pin_sck, mosi=pin_mosi, miso=pin_miso)
+
+# Callback for receiver
+buf = bytearray(300)  # Read buffer
+
+
+def receive(nbytes):  # Soft ISR runs when data received.
+    print(f"Received: {nbytes} bytes:")
+    print(bytes(buf[:nbytes]))
+    print()
+
+
+# Pins for slave
+mosi = Pin(0, Pin.IN)
+sck = Pin(1, Pin.IN)
+csn = Pin(2, Pin.IN)
+piospi = SpiSlave(callback=receive, sm_num=4, mosi=mosi, sck=sck, csn=csn)
+
 # SPI send a passed buffer
-def send(cs, spi, obuf):
+def send(obuf):
     cs(0)
     spi.write(obuf)
     cs(1)
     sleep_ms(100)
 
 
-buf = bytearray(300)  # Read buffer
-
-# Callback runs when transfer complete (soft ISR context)
-def receive(nbytes):
-    print(f"Received: {nbytes} bytes:")
-    print(bytes(buf[:nbytes]))
-    print()
-
-
 def test():
     obuf = bytearray(range(512))  # Test data
-    cs = Pin(17, Pin.OUT, value=1)  # Ensure CS/ is False before we try to receive.
-    # Pins for slave
-    mosi = Pin(0, Pin.IN)
-    sck = Pin(1, Pin.IN)
-    csn = Pin(2, Pin.IN)
-    piospi = SpiSlave(callback=receive, sm_num=4, mosi=mosi, sck=sck, csn=csn)
-    # Pins for master
-    pin_miso = Pin(16, Pin.IN)  # Not used: keep driver happy
-    pin_sck = Pin(18, Pin.OUT, value=0)
-    pin_mosi = Pin(19, Pin.OUT, value=0)
-    spi = SPI(0, baudrate=10_000_000, sck=pin_sck, mosi=pin_mosi, miso=pin_miso)
 
     print("\nBasic test\n")
     piospi.read_into(buf)
-    send(cs, spi, obuf[:256])
+    send(obuf[:256])
     piospi.read_into(buf)
-    send(cs, spi, obuf[:20])
+    send(obuf[:20])
     print("\nOverrun test: send 512 bytes, rx buffer is 300 bytes.\n")
     piospi.read_into(buf)
-    send(cs, spi, obuf)
+    send(obuf)
     print("\nTest subsequent transfers\n")
     piospi.read_into(buf)
-    send(cs, spi, b"The quick brown fox jumps over the lazy dog")
+    send(b"The quick brown fox jumps over the lazy dog")
     piospi.read_into(buf)
-    send(cs, spi, b"A short message")
+    send(b"A short message")
     piospi.read_into(buf)
-    send(cs, spi, b"A longer message")
+    send(b"A longer message")
     print("\nDone")
 
 
-test()
+try:
+    test()
+finally:
+    piospi.deinit()

rp2/spi/spi_slave.py

@@ -93,7 +93,7 @@ class SpiSlave:
         self._rinto(self._buf)
         while not self._read_done:
             pass
-        return self._buf[: self._nbytes]
+        return self._mvb[: self._nbytes]
 
     # Initiate a nonblocking read into a buffer. Immediate return.
     def read_into(self, buf):
@@ -120,6 +120,7 @@ class SpiSlave:
         self._dma.active(0)
         self._sm.put(0)  # Request no. of received bits
         if not self._sm.rx_fifo():  # Occurs if ._rinto() never called while CSN is low:
+            # a transmission was missed.
             # print("GH")
             return  # ISR runs on trailing edge but SM is not running. Nothing to do.
         sp = self._sm.get() >> 3  # Bits->bytes: space left in buffer or 7ffffff on overflow
@@ -137,3 +138,7 @@ class SpiSlave:
         self._rinto(buf)  # Start the read
         await self._tsf.wait()  # Wait for CS/ high (master signals transfer complete)
         return self._nbytes
+
+    def deinit(self):
+        self._dma.active(0)
+        self._sm.active(0)

rp2/spi/tx.py

@@ -1,3 +1,8 @@
+# spi.tx.py Send data to SPI slave
+
+# Released under the MIT License (MIT). See LICENSE.
+# Copyright (c) 2025 Peter Hinch
+
 from machine import Pin, SPI
 from time import sleep_ms
 
@@ -13,9 +18,7 @@ spi = SPI(0, baudrate=10_000_000, sck=pin_sck, mosi=pin_mosi, miso=pin_miso)
 def send(obuf):
     cs(0)
     spi.write(obuf)
-    # sleep_ms(10)
     cs(1)
-    # print("sent", obuf)
     sleep_ms(1000)