Hi, Alan,
I don’t see my I2C virtual bus driver code in the current repo. I’m not sure
what happened, but I’d like to [re-] submit it. Can you point me to how that’s
done today? (I’m sure email won’t work).
The problem I see with the existing IOEXPANDER code is that I don’t believe
it’s thread safe (multiple threads each hammering its own sensor on different
sub buses).
Cheers,
-david
> On Oct 5, 2023, at 6:18 AM, Alan C. Assis <acas...@gmail.com> wrote:
>
> Hi David,
>
> I think you figure out Gustavo's mistake.
>
> Gustavo, all you need to do is use the existing driver. In your code
> you was trying to implement a low level driver to communicate with
> your PCF8575. You don't need to do it.
>
> Unfortunately there is not much boards examples using IOEXPANDER (shame on
> us).
>
> But I think Mateusz (raiden00) created one here:
> boards/arm/nrf52/thingy52/src/nrf52_sx1509.c
>
> Just look this example and you will figure out everything.
>
> Basically:
>
> struct pcf8575_config_s g_pcf8575_cfg
> {
> .address = 0x71; /* the I2C address returned by i2ctool */
> .frequency = 100000;
> };
>
> ...
>
> int stm32_pcf8575_initialize(void)
> {
> struct i2c_master_s *i2c = NULL;
> struct ioexpander_dev_s *ioe = NULL;
> int ret = OK;
>
> i2c = stm32_i2c_register(I2C_BUS); /* I2C_BUS is your I2Cx bus
> number (0, 1, etc) */
>
> ioe = pcf8575_initialize(i2c, &g_pcf8575_cfg);
> ...
>
> }
>
> BR,
>
> Alan
>
> On 10/5/23, David S. Alessio <david.s.ales...@gmail.com> wrote:
>> 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 <spudan...@gmail.com> 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.
>>
>>
