UART interrupts McASP

Dear Sherry,
Which example are you using ?
You can also refer PSP drivers which is using BIOS.
C:\ti\pspdrivers_01_30_00_06\packages\ti\pspiom\examples\evmOMAPL138\uart

I have used I2C0 for the on-board codec. I did not use EDMA, Instead I use simple ping-pong buffering for a stereo channel, as demonstrated in C6000 Embedded design workshop videos. The starterware example is wayy too obfuscated for my humble understanding. Please see my code attached. The only PINMUX conflict was between UART2 and AMUTE pin of MCASP. I am not using RTS CTS of UART2.

audio_C6000_buffer_LR_download.rar

Please see the ISR of UART

void UART_ISR(void) {
	//Log_info0("UART_ISR");
	uart2->IER = 0;		// disable I2S interrupt temporarily
	i = UART2Read();
	UART2RInt(0);
	switch (i) {
	case 0x02:
		downloadFilter();	//branch out to another function
		break;
	case 'E':
		UART2Write(0x45);	//Echo back E
		break;
	default:
		UART2Write(0xAE);	//if anything else sent, send back AE
		break;
	}
	UART2RInt(1);	//enable RX int
}

The code works fine when i send 'E' (i.e. byte 0x45) or anything. but as soon as a byte 0x02 is sent and subsequent code is executed, McASP goes into under-run error .

inline void downloadFilter() {
	/* Mute the codec by writing on codec register number 7. 
	 * Receive bytes to make 16 bit words.
	 */
	AIC3106_writeRegister(7, (0 << 7) |// fs(ref) = 48kHz (needed only for AGC time constants, not used)
					(0 << 6) |	// ADC dual rate mode is disabled
					(0 << 5) |	// DAC dual rate mode is disabled
					(0 << 3) |	// left DAC datapath plays left channel input data
					(0 << 1) |	// right DAC datapath plays right channel input data
					(0 << 0));	// reserved
	uint8_t rxByte[4];
	rxByte[1] = UART2Read();
	rxByte[0] = UART2Read();
	loopSize = ((uint16_t) rxByte[1] << 8) | rxByte[0];	//number of filter coefficients
	rxByte[1] = UART2Read();
	rxByte[0] = UART2Read();
	wordSize = ((uint16_t) rxByte[1] << 8) | rxByte[0];	//32 bit/24 bit/16 bit
	Log_info2("xstat:[%x] ,rstat:[%x]", mcaspRegs->XSTAT,mcaspRegs->RSTAT);

}

Hi Sivaraj,
In step 1, you are enabling all clock error interrupts but in step 4, XINTCTL and RINTCTL only have data interrupts enabled. How would they work together?
I have followed your guidelines and also sections of 23.3.x in Technical reference manual. The McASP works fine if there is no other interrupt on the horizon.
In my code, (please please see the .rar project I attached) The mcasp comes back from UART interrupt if the ISR sequence is very short, but if it is long, the MCASP module misses the sampled data and goes into underrun/over run state, how can I download a long stream of bytes (4096 bytes at 115200 baudrate) ? Meanwhile, the MCASP should ignore the incoming audio sample data and put outgoing data to be zero (or mute the codec). Once UART's ISR is finished, then McASP and codec can go back to execution.

This is a BIOS system. UART interrupt is mapped to CPU interrupt with higher priority than MCASP interrupt service routine... but McASP somehow needs to PAUSE or be restarted while UART is working. I hope i rephrased my problem more specifically :-)

Sivaraj,
It is still not working. I have used your guidelines as follows:

1. TX/RX state machines of MCASP are paused and serialisers are cleared before the long ISR of UART starts.

2. State machines and Serialisers are resumed after UART is serviced.

Please see the UART_ISR below

void UART_ISR(void) {
	//Log_info0("UART_ISR");
	uart2->IER = 0;		// disable interrupt temporarily
	i = UART2Read();
	UART2RInt(0);	//Disable RX interrupts
	switch (i) {
//http://www.utf8-chartable.de/
	case 0x02:
		downloadFilter();      //Branch out -> problem here
		break;
	case 'E':
		UART2Write(0x45);	//echo back 'E'
		break;
	default:
		UART2Write(0xAE);       //echo back byte 0xAE
		break;
	}
	UART2RInt(1);	//enable RX interrupt
}

The 'downloadFilter' function works like this:

inline void downloadFilter() {
	McASP_hold();     //Put MCASP state machine in reset state and clear the serialiser
	uint8_t rxByte[4];
	rxByte[1] = UART2Read();
	rxByte[0] = UART2Read();
	loopSize = ((uint16_t) rxByte[1] << 8) | rxByte[0];	//combine the bytes to make 16 bit word
	McASP_resume();
}

The McASP_hold and McASP resume toggle the Global Control register of MCASP module. The bits are toggled are for RX/TX state machines and serialisers.
Please see the code here:

void McASP_hold(void) {
	mcaspRegs->XSTAT = 0x0000FFFF;
	mcaspRegs->RSTAT = 0x0000FFFF;
	//		while ((mcaspRegs->RSTAT & 0x0000FFFF) != 0);
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSRCLR, 0);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSRCLR)
			!= CSL_MCASP_GBLCTL_XSRCLR_ACTIVE)
		;
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSRCLR, 0);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSRCLR)
			!= CSL_MCASP_GBLCTL_RSRCLR_ACTIVE)
		;
	//only for polling
		mcaspRegs->XBUF13 =0;
	//Verify that all TX buffers are serviced, wait for XDATA to clear
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSMRST, 0);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSMRST)
			!= CSL_MCASP_GBLCTL_XSMRST_ACTIVE)
		;
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSMRST, 0);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSMRST)
			!= CSL_MCASP_GBLCTL_RSMRST_ACTIVE)
		;
}
void McASP_resume(void) {
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSRCLR, 1);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSRCLR)
			!= CSL_MCASP_GBLCTL_XSRCLR_ACTIVE)
		;
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSRCLR, 1);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSRCLR)
			!= CSL_MCASP_GBLCTL_RSRCLR_ACTIVE)
		;
	//only for polling
		mcaspRegs->XBUF13 =0;
	//Verify that all TX buffers are serviced, wait for XDATA to clear
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSMRST, 1);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_XSMRST)
			!= CSL_MCASP_GBLCTL_XSMRST_ACTIVE)
		;
	CSL_FINS(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSMRST, 1);
	while (CSL_FEXT(mcaspRegs->GBLCTL, MCASP_GBLCTL_RSMRST)
			!= CSL_MCASP_GBLCTL_RSMRST_ACTIVE)
		;

}

It has no Underrun run if ISR branch is short (e.g. transmitting any character that simply echoes back, but when '02 55 66' is sent to TI-DSP56321 board, it goes into downloadFilter() execution, and it puts the bytes correctly into the 'loopSize' variable. But the McASP goes into TX/RX error.  

Hi,

Glad to hear that works!

Thanks for your update.

Hereby, closing your post.

Regards,

Sivaraj K