Porting

This guide is a work in progress

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The steps below are cumulative. For example, if you need to do a type 3 port, you would also need to do steps 1-2. Consequently, it is the easiest to do port to a different package for an existing chip.

Identifying your chip

The STM32 chip part numbers are of the form:

STM32|<CHIP_ID>|<PACKAGE>|<FLASH_SIZE>

For example, for STM32F405RG: CHIP_ID = F405, PACKAGE = R, FLASH_SIZE = G

In the language of the Koduino libraries (and the Arduino 1.5+ hardware spec) there are only "variants". Some variants and (a non-exclusive list of) chips that fall under it are listed below:

Variant (in Koduino libraries)	Series	MCU	Chip IDs
f301	STM32F30x	STM32F302x8	F301, F302
f303v	STM32F30x	STM32F303xC	F303V
f37x	STM32F37x	STM32F37x	F373, F378
f446	STM32F4xx	STM32F446xx	F446V
f40_41x	STM32F4xx	STM32F40_41xxx	F405, F407, F417
f10x (not working yet)	-	-
f411 (not working yet)	STM32F4xx	STM32F411xE	F411
f429_439 (not working yet)	STM32F4xx	STM32F429_439xx	F429, F439

Choose:

1. New package

2. New variant

A variant corresponds to a subdirectory of koduino/variants. You need a new variant in the following cases:

• If a different startup script is required, a new variant should be defined. E.g. within the F4 series, F40_41x and F411x need different variants. This is actually a necessity, since if you put different startup .S scripts in the variant directory, the Arduino IDE will compile all files in the directory.
• Usually a different memory size

2.1 Generating variant.cpp

Unfortunately, which pins are able use analogRead, which timers need to be activated for analogWrite needs to be manually set up for a new chip.

I find that this process is made easier with spreadsheets, examples of which are in the table below:

Variant	Pin map	Timer map
f37x (done manually)	-	-
f40_41x	f40_41x_PIN_MAP	f40_41x_TIMER_MAP
f411 (needs to be checked)	f411_PIN_MAP	f411_TIMER_MAP
f10x (in progress)	f10x_PIN_MAP	f10x_TIMER_MAP

Follow these steps:

• Create a spreadsheet pair as above (f40_41x is the best example) for the targeted chip using the datasheet
• To go with these spreadsheets, there is a python script called variant_codegen.py in the variants directory which prints out C code that can be pasted into variant.cpp and variant.h
• The USARTx_TX, RX pins need to be manually entered in the definition of USART_MAP
• TIMEBASE_MAP configures timers used for attachTimerInterrupt. At least one of them must be configured for the system clock (millis(), micros(), delay() will not work otherwise).
• Set SYSCLK_TIMEBASE to the array index into TIMEBASE_MAP that should be the system clock. The actual timer peripheral that should be used (can be a basic timer, per ST datasheet) is configured in the first section of variantInit().
• The interrupt handlers must be configured in stm32fxxx_it.c. At a minimum, make sure that the system clock ISR is pointing to the correct timer. For an example, please see an existing variant such as f37x or f40_41x.

3. New memory size for existing chip

Need new startup .S file

4. New chip in existing series

5. New series