i2s / SDIO pins exposed?


Being at a lack of a schematic that I could look through, I was wondering if it will be possible to access the STM32F103’s i2s(not i2c) bus to attach a high quality DAC or ADC?
The same goes for the SDIO feature that some of the variants of the STM32F103 seem to have. If the the SDIO were accessible, it would be possible to attach an SD card in 4 bit mode to get some really nice throughput from an sd card (for example to serve files such as jquery sources if in a closed environment where it wouldn’t be feasible to pull jquery etc *.js from another source. )


Hello Nik,
The Spark Core uses STM32F103CBT6 medium density version which does have SPI (and is exposed) but not the i2s peripheral.

All of the Schematics are available on GitHub:
Spark Core: https://github.com/spark/core
Shields: https://github.com/spark/shields

Hope this helps.


Thanks for the link to the schematics, Mohit!

Apparently the sparkcore uses the SPI2 bus and brings it out to the pins, which is according to the datasheet
multiplexed with the i2s module.

Inter-integrated sound (I2S)
Two standard I2S interfaces (multiplexed with SPI2 and SPI3)


@nbd Are you sure you’re looking at the datasheet for the STM32F103CBT6? I’m fairly sure it doesn’t have an I2S peripheral.

Aww yes, you guys are of course right, sorry. I was looking at the high-density part feature lists, while the STM32F103CBT6 is in fact only a medium-density device. Features of the medium-density parts
according to the datasheet:
3 × USARTs
3 × 16-bit timers
2 × SPIs, 2 × I2Cs, USB, CAN, 1 × PWM timer
2 × ADCs

so, no I2S.