Is 400kbps(51200 bytes/seconds) the high speed of i2c on nrf52832?

[min_yuan]

Hi,

I'm wonder  is the speed of i2c on nrf52832 can be faster then 400kbps? even use EasyDMA, the speed still can't faster then 400kbps? I also look into the max speed of the SPI, it is 8Mbps(1048576 bytes/second), but still not enough.

thanks!

[Turbo J]

What hardware is on the other end of the bus?

I2C requires much more complex fast mode plus tranceivers for >400kHz - I've seen these mostly on NXP chips. Basically the pullup resistors cannot pull the bus fast enough from 0 to 1.

Faster SPI is available on the NRF52840 - but be sure to check the errata.

[min_yuan]

Hi Turbo, 

Thanks for you quick reply! The other end of the bus is MCP4725, every voltage output need 3 bytes, so in the max speed(400 kbps), only can  change   the voltage of the DAC about 17066 times/second. I want to post voltage change call  9 times/us

[min_yuan]

I'm new to embedded development, no idea which way can post a high speed DAC output, e.g 9 times/us, thanks!

[Turbo J]

Back to the drawing board.. for new component selection.

Choose a parallel DAC and either FPGA or high power µC (think 600MHz i.MX here for example). Only those can supply the DAC with data fast enough - via DMA to GPIO pins.

NRF chips do not have a DMA-to-GPIO mode AFAIK. You can still use the NRF chip for BT LE or other 2.4GHz radio stuff.