Parallel interface for 8-bit DAC

[StepMaker]

I'm investigating use of Spresense to drive a DAC (8-bit) for signal generation purposes, but it's not clear whether 5-10 MByte/sec is possible. Any pointers to appropriate interface spec and usage guidelines and/or has anyone done anything similar?

Many thanks in advance.

[TE-KarlKomierowski]

@StepMaker what DAC is it that you would like to connect? Datasheet? And what interface on Spresense would you like to use?

Br
Karl

[StepMaker]

Hi Karl, I'm hoping to start using a TLC7524/AD7524 DAC which has an 8-bit, parallel interface, then increase number of bits in future depending on what's possible. Hence, I wondered what was possible using the GPIOs, but I'm open to other I/F suggestions. If I can't drive it directly via a parallel I/F, then using SPI and a shift register (74HC595) is another option as I should be able to get the speed I need (just!). Many thanks.

[TE-KarlKomierowski]

Hi @StepMaker

I think that writing a driver in Nuttx would be the way to go.
If you have a look SDK in a file sthat is called /nuttx/boards/arm/cxd560xx/spresense/src/cxd56_gpioif.c you will se how the board_gpio_write function is written.
if you can find 8 GPIO pins that are access by the same register you should be able to write to all 8 of them with one register write. This I think should give you proper speed.

This way is a little bit tricky but I think it should be doable.
I would give it a try, and you can always come back if you have more questions.

Br
Karl

@StepMaker said in Parallel interface for 8-bit DAC:

I'm investigating use of Spresense to drive a DAC (8-bit) for signal generation purposes, but it's not clear whether 5-10 MByte/sec is possible. Any pointers to appropriate interface spec and usage guidelines and/or has anyone done anything similar?
Many thanks in advance.

[StepMaker]

Many thanks again Karl. I'll give the gpio_write a go as well as I'll try using SPI interface and a shift register. I'll share progress.