STM8AF51A9 64-Pin Package Port E Issue

jstramaglia · ‎2009-05-07

Posted on May 07, 2009 at 19:57

jstramaglia · ‎2011-05-17

Posted on May 17, 2011 at 15:03

I'm using a STM8AF51A9 in the 64-Pin Packageand have run into an issue using Port E for GPIO. The 2 pins assigned to the I2C port refuse to respond to PE_ODR commands. The Port pins are configured as All Output - All Push-Pull. Sending a command of All High leaves both Port Pins E1 and E2 as Low. The Dis-Assembly shows (during debug) that the ASM is issuing the correct command and a read-back of the Port E ODR Register indicates that it latched the value correctly.

I read the info regarding the I2C config registers and thought that maybe the reset value wasn't correct, I set the register I2C_CR1 to zero and read it back as zeros.

Is there any errata for this device that would indicate a work around?

Joe

jstramaglia · ‎2011-05-17

Posted on May 17, 2011 at 15:03

Never Mind,

I just saw in the data sheet that these pins are true open drain and do not have the P-Buffer implemented. The original display that was going to be used in the design was I2C, hence the choice to use these pins, but a display change meant bit-banging the output. Which I now see isn't going to work do to the open drain.

My mistake, but I'll leave the message up in case anyone else misses this in the datasheet.

Joe