SPI with LS7366R

RE: SPI with LS7366R

Hakon — Mon, 31 Jan 2022 16:07:35 GMT

You can probably do something like what is done in this case, where the pin is configured to H0D1 (high drive 0, disconnect 1).

RE: SPI with LS7366R

jopayne24 — Mon, 24 Jan 2022 21:40:41 GMT

Thanks Hakon.

I see Zephyr GPIO documentation related to pin voltage flags - nothing about pin amperes or high-drive specifically . Is there a standard method for setting SPI pins to high drive through zephyr APIs/device tree configs given nrf_gpio_cfg is not available with my current approach?

RE: SPI with LS7366R

Hakon — Mon, 24 Jan 2022 14:17:14 GMT

Perhaps you can try setting all the pins to high drive (SCK/MISO/MOSI). Also, you can consider doing a logic trace when using 2MHz or greater frequency, to see what it looks like.

RE: SPI with LS7366R

jopayne24 — Sat, 22 Jan 2022 00:08:47 GMT

To update, I did get this working.

I moved away from "standard drive" GPIOs (which I don't believe made a difference, as it seems using those at frequencies above 10kHz isn't a limitation, but rather, a recommendation due to potential radio interference), but more importantly, I reduced the SPI frequency from the attempted 2MHz down to the minimum 125kHz and worked my way up. I did move from SPI1 to SPI3, but I think that only makes a difference if you're looking for SPI frequencies greater than 8MHz (i.e., I was just trying different things).

This leads to my follow-up question:

The counter reads/writes over the bus without issue if I compile with a SPI frequency of 1.99MHz or less. If I attempt 2MHz or greater, the LS7366r stops responding to my count calls (assumedly my writes to the configuration registers don't take either) just as it did in my main post above.

Obviously this sounds like a limitation of the counter, but I slapped together an app on esp-idf that had no trouble at 2-4MHz, and the breadboards manufacturer's Arduino library for the chip runs at 4MHz without issue. The manufacturer also states that the breadboard the LS7366r is on can handle 20MHz due to the particular oscillator they mounted (the IC itself can go up to 40MHz when powered via 5v).

Is there a limitation with Zephyr regarding the SPI frequency or, again, something screwy with my configure? I read the nrf52840 isn't supported by Nordic re: Zephyr. Is that true? If so, I can close this ticket and stop hassling everyone.

RE: SPI with LS7366R

jopayne24 — Tue, 18 Jan 2022 19:58:47 GMT

Hi. I'm powering on J2, J-link USB.

RE: SPI with LS7366R

Hakon — Tue, 18 Jan 2022 14:15:30 GMT

Hello,

Are you powering the board through J-Link USB, or VDDH?