McASP works but not as suggested by C6000 workshop labs. I can't understand why?
I have three functions associated to McASP in LCDKc6748.
fxn: McASP_init()) --> to set up register values of McASP
fxn: McASP_start() to activate serializers and clocks.
fxn: ISR for McASP stereo audio In/out to be called by SYS/BIOS
Case 1:
When McASP_init() and McASP_start() are called before BIOS_start(), there is silence on codec. ISR not called!
Case 2:
If instead of interrupt based program, it is polling based ...XBUFn are serviced during McASP start up as guided by Technical reference manual of C6748..... then it works fine. Polling is achieved by making no changes to initialization sequence but JUST introducing a while(1) loop after call of McASP_start() and before BIOS_start()--> Hence SYS/BIOS never starts.. Inside the while(1) loop, mcasp XSTAT and RSTAT are checked and XBUFn and RBUFn are written accordingly. This works fine.
Case 3:
If the function call to McASP_start() is removed before BIOS_start() and instead it is called as a task with following loop at the end of it.
while(1)
{
//Stay here after McASP_start has activated all clocks and serialisers
}
In this case the ISR is called perfectly fine with no TX/RX underrun or over run. The ISR services the XSTAT[XDATA] when the clocks, frame sync, state machines are activated by McASP_start();
Why is that? Why can't McASP_start() work properly ? please see my project attached.
None of the registers are changed while the calls change.
Please see the main.c code
void main(void) {
// Key to be written to enable the pin mux registers for write
sysRegs->KICK0R = 0x83e70b13;
sysRegs->KICK1R = 0x95A4F1E0;
// Using PINMUX utility, RTS ignored AMUTE is kept
sysRegs->PINMUX0 = 0x41111111;
sysRegs->PINMUX1 = 0x10011111;
sysRegs->PINMUX2 = 0x00000001;
sysRegs->PINMUX4 = 0x00222200;
// UART SETUP ---------------------------------------------
UART2Power(); //CPU interrupt #7 for app.cfg
UART2Default();
// I2C SETUP ----------------------------------------------
I2C_init(1); //400K I2C_SCK clock
// McASP SETUP --------------------------------------------
McASP_init(48000, 16); // CPU interrupt #5 for app.cfg
// Codec initialise ---------------------------------------
AIC3106_Init_TTO(48000, 16); //Fs=48000 and word size = 32 bits
McASP_start(); //use during polling
//
// // =======================polling code=========================================
// while (1) // loop forever
// {
// if (mcaspRegs->XSTAT & 0x00000020) // If Tx data ready flag is up
// {
// if (mcaspRegs->XSTAT & 0x00000040) // start of frame
// {
// mcaspRegs->XBUF13 = mcaspRegs->RBUF14;
// mcaspRegs->XSTAT = 0x00000040;
// }
// else // if it is last slot of frame
// {
// mcaspRegs->XBUF13 = mcaspRegs->RBUF14;
// mcaspRegs->XSTAT = 0x00000010;
// }
// mcaspRegs->XSTAT |= 0x00000020; // clear XDATA flag
// }
// }
BIOS_start(); // start BIOS Scheduler (never returns)
}
