07-27-2016, 12:41 PM
(This post was last modified: 07-27-2016, 12:45 PM by martinayotte.)
The EnableI2cPullup.c is doing much more than just adding PullUps on I2C GPIOs, it seems to do the same with all those GPIOs :
PC5,PC9,PH2,PH3,PH5,PH6,PL8,PL9
There 2 I2C in the list, the PH2/PH3 which are TWI1 (btw, TW0 on PH0/PH1 seems to have been forgotten), and PL8/PL9 which is S_TWI, not defined or initialised yet in the Kernel.
So, I doubt that POT boards are using S_TWI, but simply using the TWI1 on PiHeader pins 3/5 instead of pins 27/28.
Maybe someone can verify the traces on the board, I don't have such board and Wiki doesn't provide schematic for this ...
For the other GPIOs which PullUps have been initiaized, PC5/PC9/PH5/PH6, I don't know why they have done that (for PH5/PH6 maybe to prevent breaks on UART3, but no other UARTs have that done).
Last thing, if S_TWI on pins 27/28 is really useful, than the current DTS of the Kernel will need to provides new entries which will bring it probably as /dev/i2c-4.
BTW, for the TWI1, it would be probably pretty easy to have the pullup mode done directly in the DTS too, but why there are external pullups on those pins already ?
PC5,PC9,PH2,PH3,PH5,PH6,PL8,PL9
There 2 I2C in the list, the PH2/PH3 which are TWI1 (btw, TW0 on PH0/PH1 seems to have been forgotten), and PL8/PL9 which is S_TWI, not defined or initialised yet in the Kernel.
So, I doubt that POT boards are using S_TWI, but simply using the TWI1 on PiHeader pins 3/5 instead of pins 27/28.
Maybe someone can verify the traces on the board, I don't have such board and Wiki doesn't provide schematic for this ...
For the other GPIOs which PullUps have been initiaized, PC5/PC9/PH5/PH6, I don't know why they have done that (for PH5/PH6 maybe to prevent breaks on UART3, but no other UARTs have that done).
Last thing, if S_TWI on pins 27/28 is really useful, than the current DTS of the Kernel will need to provides new entries which will bring it probably as /dev/i2c-4.
BTW, for the TWI1, it would be probably pretty easy to have the pullup mode done directly in the DTS too, but why there are external pullups on those pins already ?