So yeah, we fixed the linux development and programming tools for the STM32 series of ARM cortex M3 chips. And I spent quite a few weeks getting distracted by the tools, and never got around to actually developing for the platform.

Today I sat down to try and wire up a Microchip MRF24J40MA 802.15.4 module to the STM32L discovery board. Seemed straight forward enough, “what pins are for SPI”

“…..” What the… These pins could be anywhere! The reference manual doesn’t say, it refers to the datasheet, which has a table, “Table 5, Alternate function input/output” on page 35 of the actual device datasheet, revision 4. That table says that there are two SPI ports, and they can be made available on a variety of pins. Apparently, SPI1 and SPI2 can be made available on two separate sets of pins each!

All well and good, but how? That’s for another day :)