esp-idf/docs/api-guides/romconsole.rst

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ESP32 ROM console
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When an ESP32 is unable to boot from flash ROM (and the fuse disabling it hasn't been blown), it boots into a rom console. The console
is based on TinyBasic, and statements entered should be in the form of BASIC statements. As is common in the BASIC language, without a
preceeding line number, commands entered are executed immediately; lines with a prefixed line number are stored as part of a program.
Full list of supported statements and functions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
System
------
- BYE - *exits Basic, reboots ESP32, retries booting from flash*
- END - *stops execution from the program, also "STOP"*
- MEM - *displays memory usage statistics*
- NEW - *clears the current program*
- RUN - *executes the current program*
IO, Documentation
-----------------
- PEEK( address ) - *get a 32-bit value from a memory address*
- POKE - *write a 32-bit value to memory*
- USR(addr, arg1, ..) - *Execute a machine language function*
- PRINT expression - *print out the expression, also "?"*
- PHEX expression - *print expression as a hex number*
- REM stuff - *remark/comment, also "'"*
Expressions, Math
-----------------
- A=V, LET A=V - *assign value to a variable*
- +, -, \*, / - *Math*
- <,<=,=,<>,!=,>=,> - *Comparisons*
- ABS( expression ) - *returns the absolute value of the expression*
- RSEED( v ) - *sets the random seed to v*
- RND( m ) - *returns a random number from 0 to m*
- A=1234 - * Assign a decimal value*
- A=&h1A2 - * Assign a hex value*
- A=&b1001 - *Assign a binary value*
Control
-------
- IF expression THEN statement - *perform statement if expression is true*
- FOR variable = start TO end - *start for block*
- FOR variable = start TO end STEP value - *start for block with step*
- NEXT - *end of for block*
- GOTO linenumber - *continue execution at this line number*
- GOSUB linenumber - *call a subroutine at this line number*
- RETURN - *return from a subroutine*
- DELAY - *Delay a given number of milliseconds*
Pin IO
------
- IODIR - *Set a GPIO-pin as an output (1) or input (0)*
- IOSET - *Set a GPIO-pin, configured as output, to high (1) or low (0)*
- IOGET - *Get the value of a GPIO-pin*
Example programs
~~~~~~~~~~~~~~~~
Here are a few example commands and programs to get you started...
Read UART_DATE register of uart0
--------------------------------
::
> PHEX PEEK(&h3FF40078)
15122500
Set GPIO2 using memory writes to GPIO_OUT_REG
---------------------------------------------
Note: you can do this easier with the IOSET command
::
> POKE &h3FF44004,PEEK(&h3FF44004) OR &b100
Get value of GPIO0
------------------
::
> IODIR 0,0
> PRINT IOGET(0)
0
Blink LED
---------
Hook up an LED between GPIO2 and ground. When running the program, the LED should blink 10 times.
::
10 IODIR 2,1
20 FOR A=1 TO 10
30 IOSET 2,1
40 DELAY 250
50 IOSET 2,0
60 DELAY 250
70 NEXT A
RUN
Credits
~~~~~~~
The ROM console is based on "TinyBasicPlus" by Mike Field and Scott Lawrence, which is based on "68000 TinyBasic" by Gordon Brandly