CC2540: BLE Stack Interrupt loss issue

Hi,

Thanks for your response. As mentioned I am using the simpleBLEPeripheral example code from TI. The serial port is connected to a cellular modem, and I am sending in a loop a test message comparing the results to what is expected ind signal if something is wrong. As long at the BLE advertising is off - everything runs smoothly, no errors, no interrupt losses, as soon as I turn on the Advertisement I am starting to loose data from time to time.

This is the UART initialization code:

/******************************************************************************
* @fn CellInit
*
* @brief Initialize the UART for the Cellular Module Communication
*
* @param none
*
* @return none
*****************************************************************************/
void CellInit()
{
U1CSR = 0xC0;
//U1BAUD = BAUDM_57600;
//U1GCR = BAUDE_57600;
U1BAUD = BAUDM_115200;
U1GCR = BAUDE_115200;
current_rx_buf = 0;
UARTrxLen[0] = 0;
UARTrxLen[1] = 0;
IP0 |= 8; // Heigher UART1 interrupt priotity
IP1 |= 8;
// Enable RX interrupts
URX1IE = 1;
}

Here is the UART Interrupt section:

#define SYNC_CHAR 'K'
char rx_error;
char s;
bool sync = true;
char exp_str[] = {"\r\nat+cops?\r\r\n+COPS: 0,0,\"Partner\",0\r\n\r\nOK"}; // Expected string
// UART1 RX Interrupt
HAL_ISR_FUNCTION(HalUARTrxIsr,URX1_VECTOR)
{
cmd_req = 1; // This marks enterinh the ISR for LA recording
cmd_req = 0;
//task_hold = 3;
char c = U1DBUF;
if (sync)
{
if (c == SYNC_CHAR) { sync = false; s = 0;}
} else
if ( exp_str[s++] != c)
{
sel = 0; // Test - marks an error for LA recording
rx_error++;
sync = true;
sel = 1; // Turn off marking
}
if (s == sizeof(exp_str) -1) s = 0;

if (UARTrxLen[current_rx_buf] == UART_BUF_LEN/2) {
rx_overflow = true;
return;
}
UARTrxBuf[current_rx_buf][UARTrxLen[current_rx_buf]++] = c;

}

Regards,

Eitan

Hi,

Thanks, I will wait for the response. In the meantime I further investigated this issue and identified a very strange behavior, it looks like its not that the interrupts are disabled but more like the CPU clock speed is changed to a very low speed or maybe the CPU halts - I conclude this because if this phenomena happens during serial port transmission - the transmission stops for a while and in practice the data is corrupted if it happens in the middle of a character transmission.  Also If I starts a counter, the counting of this counter stops and the timing is incorrect.

Best Regards,

Eitan

Sean,

I would like to add some more data, maybe it will helping you to analyze this issue, it seems like the source of the problem is not loosing interrupts but the CPU clock changed. It looks like the CPU clock is divided by 32 at certain time when advertising. Look at the picture below - it depicts an output of a free running counter configured to toggle every 256 CPU clocks i.e. the frequency is 25Mhz / 512 = 62.5 Khz. During advertising the CPU clock is divided by 32 - i.e. instead of 32Mhz it is only 1 Mhz. This results in undesired behavior such as the serial port baud rate is now 1/32 than the desired rate, if there is a receive or transmit during this period the data is corrupted.   

Best Regards,

Eitan