OK - so I just started with these chips, and have been asked to find out why SWO debug signal is getting corrupted.
At fairly random intervals the signal passive state inverts from 0 to 1, which corrupts the next few lines of debug output until the passive state inverts back again.
I suspect a silicon bug, or a conflict between something like GPIO and the ITM, but wanted to start by double-checking the hardware configuration settings.
The SWO is configured as follows, but there are quite a few magic numbers in there.
//
// brief Initialize the SWO trace port for debug message printing
// param portBits Port bit mask to be configured
//
void SWO_Init(uint32_t portBits)
{
uint32_t SWOSpeed = 57600; // baud rate
uint32_t SWOPrescaler = (CPU_CORE_FREQUENCY_HZ / SWOSpeed) + 1; // SWOSpeed in Hz, note that CPU_CORE_FREQUENCY_HZ is expected to be match the CPU core clock
CoreDebug->DEMCR = CoreDebug_DEMCR_TRCENA_Msk; // enable trace in core debug */
*((volatile unsigned *)(ITM_BASE + 0x400F0)) = 0x00000002; // "Selected PIN Protocol Register": Select which protocol to use for trace output (2: SWO NRZ, 1: SWO Manchester encoding)
*((volatile unsigned *)(ITM_BASE + 0x40010)) = SWOPrescaler; // "Async Clock Prescaler Register". Scale the baud rate of the asynchronous output
*((volatile unsigned *)(ITM_BASE + 0x00FB0)) = 0xC5ACCE55; // ITM Lock Access Register, C5ACCE55 enables more write access to Control Register 0xE00 :: 0xFFC
ITM->TCR = ITM_TCR_TraceBusID_Msk | ITM_TCR_SWOENA_Msk | ITM_TCR_SYNCENA_Msk | ITM_TCR_ITMENA_Msk; // ITM Trace Control Register
ITM->TPR = ITM_TPR_PRIVMASK_Msk; // ITM Trace Privilege Register
ITM->TER = portBits; // ITM Trace Enable Register. Enabled tracing on stimulus ports. One bit per stimulus port.
*((volatile unsigned *)(ITM_BASE + 0x01000)) = 0x400003FE; // DWT_CTRL
*((volatile unsigned *)(ITM_BASE + 0x40304)) = 0x00000100; // Formatter and Flush Control Register
}
So first question - anybody know where I can find the register definitions?
I followed this thread about SWO but it took me to the Infocenter, which has been deprecated and I cannot find a reference manual for the 52832
Thanks in advance
