Hi Alan!

 I enabled the PCF8575 driver on NuttX, I'll try to use it and get back to you 
if I need help.

Thank you!
________________________________
De: Alan C. Assis <acas...@gmail.com>
Enviado: segunda-feira, 2 de outubro de 2023 11:44
Para: dev@nuttx.apache.org <dev@nuttx.apache.org>
Assunto: Re: Writing in an I2C device

Hi Gustavo,

On 10/1/23, Gustavo Soares <gustavo.felipesoa...@hotmail.com> wrote:
> Hello everyone!
>
> I have a PCF8575 IO expander with 16 channels wich I want to use 8 for write
> (P10 to P17). The hardware is already configures and all LED's connected to
> these ports are on. As you can see, NuttX sees the I2C device:
>
> [cid:ecafac4f-7e7e-4cb1-a090-ecdc0b0d942e]
>
> Also when I run the command to read it, it returns FF (255), meaning all
> LEDs are on:
>
> [cid:03315e20-c94f-4166-922a-7512f6f6fb63]
>
> For some reason the command to write into the i2c device seems not to work:
>
> [cid:39e062d1-caf0-4128-9874-a6c2792db4fd]
>
> *I tested the i2c device and the LEDs with a simple counter program using
> visuino (https://www.visuino.com/) and it worked.
> *For NuttX, I followed the steps of this
> video<https://www.youtube.com/watch?v=RzrDa4Sm1rU>.
>
> Is the i2c set command correct? Should I apply any adicional config?
>

There is already a PCF8575 driver on NuttX.

I suggest you to try using that driver instead of play with the chip
from terminal.

Probably the error is because you are reading 1 byte by time, the chip
expects 16-bit reading.

BR,

Alan

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