QSPI issue/questions

RE: QSPI issue/questions

Adam Gerken — Tue, 21 Jul 2020 18:00:46 GMT

That stinks. I'll probably just revert to SPIM mode. I wish the QSPI module was more flexible. Thanks.

RE: QSPI issue/questions

haakonsh — Tue, 21 Jul 2020 17:33:26 GMT

I think that's a hard one.

The only solution I can think of is to manipulate the CLK and I/O lines with GPIOs during the instruction/command phase.
That would require an external multiplexer between the QSPI and RAM device.
The idea is to mask the first 6 clock cycles and injecting the instructions on the last 2.

It might require execution priority on the CPU during that time in order to bit-bang the instruction.

RE: QSPI issue/questions

Adam Gerken — Tue, 21 Jul 2020 16:02:08 GMT

Alright Haakonsh, I think I ran into a game stopper. The RAM wants the commands sent on all four data lines not just one, which I don't see how to make happen. Any ideas?

RAM:

NRF:

RAM:

NRF:

RE: QSPI issue/questions

Shahar — Mon, 20 Jul 2020 15:59:19 GMT

The nrf_qpsi which I suggested to use are the QSPI_HAL btw...

I suggested to take nrfx_qspi and as the template - as it'll give structure, and most of the stuff might be ready already (just strip away anything to do with Flash, like erase, etc.)

RE: QSPI issue/questions

Adam Gerken — Mon, 20 Jul 2020 15:57:26 GMT

Haakonsh, That's what I'm thinking too. I'll plug away on it and let you know if I run into any issues.

RE: QSPI issue/questions

haakonsh — Mon, 20 Jul 2020 14:30:12 GMT

I suggest you use the QSPI HAL directly and write your RAM driver on top of that. The QSPI driver is written for FLASH devices and you will have to remove most of the code from it anyways in order to port it to RAM.

RE: QSPI issue/questions

Shahar — Fri, 17 Jul 2020 19:47:38 GMT

An interesting question.

AFAIK you are correct assuming the nrfx_qspi module is only for handling QSPI flash module, and expects the module to respond to the QSPI op codes.

But I don't think there's any limitation on you taking the nrfx_qspi, renaming it, and modifying the code to utilize the nrf_qspi functions with your new op codes.

You'll probably only need to implement read and write, and maybe KISS by having everything done in blocking mode (as it's RAM ... and maybe no need for erase or long write/read operations)