Hi, Gustavo,
You might consider using the I2C IO expander driver I wrote some time ago to
manage a multi-tiered tree of I2C bus expanders.
The advantages are:
* I2C sub buses are transparently available to application space through
/dev/i2c*
* transparently manages hierarch of I2C bus expanders
* downstream I2C device drivers go through the I2C character driver (pro and
con)
The disadvantages are:
* I2C drivers need to use the I2C character driver
* many I2C HW drivers don’t properly handle multiple command packets in
I2C_TRANSFER()
Example: let’s say we have an 4-port I2C switch PCA9545A attached to /dev/i2c1
using an STM32F407 MCU. The board initialization would be:
i2c = stm32_i2c_register(1);
/*
* support for I2C bus epander
* /dev/i2c1.0 -- /dev/i2c1.3
*/
ret = i2c_vbus_initialize("/dev/i2c1", 0x70, I2C_VBUS_PCA9545, 0x0f, 0, NULL);
if (ret != OK)
{
syslog(LOG_ERR, "ERROR: Failed to initialize i2c_vbus %#x: %d\n", 0x70,
ret);
}
Now the sub bus I2C segments are transparently available as /dev/i2c1.0 through
/dev/i2c1.3.
You can add a second PCA9545A, let’s say connected to port 2 (/dev/i2c1.2) of
the first PCA9545A. It would be registered as:
ret = i2c_vbus_initialize("/dev/i2c1.2", 0x71, I2C_VBUS_PCA9545, 0x0f,
0, NULL);
and its ports would be addressable as /dev/i2c1.2.0 through /dev/i2c1.2.3.
Let me know if this is something of interest to you, I’ll help you get it
working...
Cheers,
-david
> On Oct 4, 2023, at 7:36 PM, Gregory Nutt <[email protected]> wrote:
>
>
> On 10/4/2023 8:02 PM, Gustavo Soares wrote:
>> Hi Greg!
>>
>> Yes, if I use #include <nuttx/ioexpander/pcf8575.h> this problem is solved,
>> but then the code loses the reference to that specific struct causing
>> another error.
>>
>> And how exactly "the file does not exist"? I can open it and it is at the
>> nuttx repo, I shared it's link.
> Because the compiler keeps a list of paths that it will include files from.
> It will NOT include files from drivers/ioexpander because that is not in that
> include path list. So "the file does not exists" in any directory in the
> list of include paths. You could hack up the build system (but no PRs for
> that please)or you could just copy the header file (a lot easier). But you
> cannot include it from drivers/ioexpander. Since this is necessarily
> throw-away code, the easier solution is recommended.
