Computing > Embedded Computing

ARM with fast parallel GPIO

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kamtar:
Hello,

I'm looking for some Cortex-M MCU which would be ideal to feed fast DAC through a parallel interface.

1. I don't want any DSP or FPGA, just a regular ARM MCU.
2. I don't have any strict minimal speeds in mind just as fast as it can be.. getting some parallel interface that could run close to 50-100Mhz would be nice.

I'm in a process of reading up on various MCUs and going over my options but if there is somebody who has used some ARM for something similar I would be glad to hear it.

SiliconWizard:
You should be able to do that with the FMC peripheral of STM32's MCUs, for instance. For 100MHz, I would suggest a STM32F7 or H7.
Now the issue there is that the speed is not the only requirement. If you're driving a parallel DAC, data has to get out at a fixed frequency with low jitter. I can't guarantee the FMC peripheral of above MCUs can get you that.

ataradov:
It is going to be a challenge. I'm looking for some ARM device with a fast parallel interface with no special protocol, but not a whole lot of luck.

Most of the time you get static memory controller, but it inserts address latch cycles, so not ideal for just transferring raw data. In some cases there is ability do disable the address cycle, but the interface speed is still not that fast. One such example is Nuvoton M480 series.

Often the best way to read/write raw data stream is camera/display interfaces. But again, in many cases controllers are too smart and expect proper hsync/vsync pulses.

For getting the data into the device I found SAM E70 to be the best. It has parallel capture controller, which boils down to 8-bit bus, external clock, and a couple enable pins.

Interfacing with FPGAs is such a common task that I don't understand why chip vendors do not include a dedicated peripheral for that, which would be also reusable as a general purpose parallel streaming interface.

NiHaoMike:

--- Quote from: SiliconWizard on January 17, 2021, 12:06:27 am ---You should be able to do that with the FMC peripheral of STM32's MCUs, for instance. For 100MHz, I would suggest a STM32F7 or H7.
Now the issue there is that the speed is not the only requirement. If you're driving a parallel DAC, data has to get out at a fixed frequency with low jitter. I can't guarantee the FMC peripheral of above MCUs can get you that.

--- End quote ---
Run it in slave mode with an external oscillator supplying the clock. That said, such a high clock rate is asking a bit much from a microcontroller, a cheap FPGA or CPLD would probably be a better solution.

kamtar:
Thanks for the inputs, I will take a look at SAM E70s.
To be more precise I don't plan driving DAC directly it's more of a DDS IC, this is just for a prototype I will use to actually figure out what everything I can do with it using the modulation registers and so on.

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