Micropy 66 i2c target implementation

[LinjingZhang]

Summary

Implement i2c target (slave) based on mpy extmod.momachine
Only 0 address is supported!

TODO:
8 bit/16 bit Memory Access mode:
https://jirard.intra.infineon.com/browse/MICROPY-82
Explore mpy ROM level feature
https://jirard.intra.infineon.com/browse/MICROPY-83

Testing

Using example in micropython doc:
Target - PSoC edge:

from machine import I2CTarget

# Define an IRQ handler, for I2C events.
def irq_handler(i2c_target):
    flags = i2c_target.irq().flags()
    if flags & I2CTarget.IRQ_END_READ:
        print("controller read target at addr", i2c_target.memaddr)
    if flags & I2CTarget.IRQ_END_WRITE:
        print("controller wrote target at addr", i2c_target.memaddr)

# Create the I2C target and register to receive default events.
mem = bytearray(8)
i2c = I2CTarget(addr=67, mem=mem)
i2c.irq(irq_handler)

Controller - PSoC 6:

from machine import I2C
scl_slave_pin = "P0_2"
sda_slave_pin = "P0_3"

i2c = I2C(scl=scl_slave_pin, sda=sda_slave_pin, freq=400000)


devices = i2c.scan()
print("Found devices:", [hex(d) for d in devices])

i2c.writeto(0x43, b'Hello')


data = i2c.readfrom(0x43, 8)
print("Read:", data)

Verify with logic analyzer:

Trade-offs and Alternatives

I've added a few modules/functions, but these are the minimum I need to use extmod I2CTarget.

[jaenrig-ifx]

Quite a lot of progress :) Well done, looks quite good as far as I can judge.
Some questions and minor discussion or things we can polish before merging to main.

[jaenrig-ifx]

Can you explain this contribution regarding the assembler flags?

[jaenrig-ifx]

How does this relates to the I2C ?

[jaenrig-ifx]

Can you explain this enablement of the garbage collector?

[jaenrig-ifx]

How are all these macros related to the I2C enablement?
Please remove all the defines that are not related to what you are working on, and you are not aware of what they control.
Usually by default, they have default values in "py/mpconfig.h" which should be consciously overwritten.

[jaenrig-ifx]

There is no default definition of MICROPY_HW_MAX_I2C or? If not MAX_I2C is defined this will not compile.

In file included from ../../extmod/machine_i2c_target.c:240:
../../ports/psoc-edge/machine_i2c_target.c:59:17: error: 'MICROPY_HW_MAX_I2C' undeclared here (not in a function); did you mean 'MICROPY_HW_MCU_NAME'?
   59 | #define MAX_I2C MICROPY_HW_MAX_I2C
      |                 ^~~~~~~~~~~~~~~~~~
../../ports/psoc-edge/machine_i2c_target.c:62:56: note: in expansion of macro 'MAX_I2C'
   62 | static machine_i2c_target_obj_t machine_i2c_target_obj[MAX_I2C];
      |                                                        ^~~~~~~
../../ports/psoc-edge/machine_i2c_target.c:62:33: error: 'machine_i2c_target_obj' defined but not used [-Werror=unused-variable]
   62 | static machine_i2c_target_obj_t machine_i2c_target_obj[MAX_I2C];
      |                                 ^~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
-e See https://github.com/micropython/micropython/wiki/Build-Troubleshooting
make: *** [../../py/mkrules.mk:101: build-KIT_PSE84_AI/extmod/machine_i2c_target.o] Error 1

[jaenrig-ifx]

mmm is that mask right? if addrsize is 7 the mask is 0b11111110 and if not 0b11111100. How does this work?

[jaenrig-ifx]

This one is not needed? How is the passed trigger by the user updated in the pdl interrupt handler?