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MC9S08PT60 SCI0 on PTA3 PTA4 TX PIN wont work

Question asked by Carl Norman on Feb 15, 2016
Latest reply on Feb 16, 2016 by Carl Norman

Hi Guys,


I have the MC9S08PT60 processor (44pin), I am using all three SCI UART modules in my application, 2 work perfectly fine (SCI1 and SCI2). SCI0_RX works, but SCI0_TX just wont work.


I have SCI0 on PTA2/3 (44pin package, pins 33/32). I changed SYS_SOPT1 bit 7 to 1 (Confirmed with debugger so mapping is correct)


  clrSetReg8Bits(SYS_SOPT1, 0x03U, 0x8CU);


Using processor expert for a really simple test I set internal clock to 16Mhz, added SCI0, added SCI1, set both to 9600baud, modified SYS_STOP1 bit 7 to 1 as above, then added basic test code just to see TX data on each SCI module


   setReg8(SCI0_C2, 0x0CU);           //Enable TE / RE

   setReg8(SCI1_C2, 0x0CU);          //Enable TE / RE



       if(SCI0_S1_TDRE) SCI0_D = 0x31;                 //Setup next byte to transmit on the comm port

       if(SCI1_S1_TDRE) SCI1_D = 0x31;                 //Setup next byte to transmit on the comm port



Using my oscilliscope and measuring the bare board PIN with nothing attached (PIN32)

SCI1 I see data on the bare output PIN perfectly fine at 9600baud

SCI0 i see nothing ever on the data PIN.


Also, I set up RX interrupts to see if the RX interrupt fires and I get valid data, which i do, on both SCI0 and SCI1! I also use this code (with no real changes other than names on the AC128 and it works in production no problem)


If I turn the pin to and output it toggles on and off no problem, and RX input works, TX/RX work on the other SCI ports. I cant find anything else you have to do to get this TX module to work, im stuck! I can only imagine there is a problem with these chips, or, some documentation I cant find.