I would like to connect the FMC interface to external 12bit, 80MHz ADC. 1. Does the STM32MP151 support such rate? 2. How should I configure the bus?

[Estei.1]

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[PatrickF]

Hello,

please precise if you plan to use this with Cortex-A7 (Linux) or Cortex-M4.

FMC is not really tailored for such usage, as I assume you want to have continuous data provided by the ADC at 80MHz rate.

FMC is intended to read data from SRAM-like device in asynchornous or synchronous way, but sound not possible to read such rate.

For Cortex-M4 side, maybe possible to use DCMI for such usage, but 80MHz is still at the edge about IP capabilities. And I' not sure ADC could connect directly.

[Estei.1]

Hi Patrick,
OK. Thanks.
What about regular GPIOs? Will they be able to be read as a bus in such rate? For example PortA[15:0]/PortB[15:0] etc?
Eyal

[PatrickF]

Hi,

GPIO input cannot be read at 80MHz. The APB bus is at 104.5MHz max and there is a need of few clock cycles to read one data (not including the time for a master such as a DMA to process it and store in memory).

Btw, which processing do you plan to have in SW on this 1Gbit/s of data (160MBytes/s assuming 2 bytes to store one 12-bit sample) ?

I fear you have to pre-process your data externally (e.g. FPGA connected on FMC, which could filter or else and drastically reduce data rate managed by the System).

Maybe have a look to QUADSPI which could read data in DDR mode at 80MHz clock. You need to be clever and have some external logic to drive 8bits on one edge and 4 bits on another one (or 6+6 if easier). But as SPI is not a continuous input, you need also external Fifo somewhere.