FMC vs FSMC

[skon.1]

Hello,

A product I'm working on requires communicating with an FPGA over an 8 bit data + 24 bit address bus.

To support a legacy design with the least possible changes I need the bus to toggle at 43.75 MHz.

All I need is single (non-burst) address accesses.

Which type of bus would you recommend for my application ? FMC or FSMC ?

[Peter BENSCH]

Well, you can meet your requirements with both FMC and FSMC. However, the prerequisite is an HCLK of at least twice your desired bus frequency, i.e. >87.5MHz, which already eliminates all older derivatives such as the STM32F1.

Of the remaining derivatives with sufficient clock frequency, there are currently about 233 that have an FSMC (F405, F407, etc), but with currently 964, there are many with the newer FMC.

So I would recommend FMC, if data also has to be transferred, possibly a Cortex-M7 based STM32 like the STM32F7 or STM32H7, maybe the brandnew STM32H5 is also sufficient.

Hope that helps?

Regards

/Peter

[skon.1]

Thanks,

That's very helpful.

Working with this document:

https://www.st.com/resource/en/reference_manual/DM00327659-.pdf#page=709&zoom=100,89,117

I'm thinking to feed the FMC peripheral with "aclk"

The "aclk" will be generated from a 43.75 MHz clock through the HSE pin that will be connected to the device's HSE pin and driven with an external oscillator clocking at 43.75 MHz (The frequencies of HSE and "aclk".will be the same)

 

Will this work ?

[skon.1]

Can someone please help with this ?