Other Parts Discussed in Thread: MSP430FG4618
Hello,
I have setup my MSP430FG4618 to send data to an OLED display over SPI. I am using IAR. I did not enable the MISO line since we are not receiving anything from the display. Here is the problem I am having.
>> Initially, the TXIFG is set since the TXBUF as well as the shift register are empty. After checking for the TXIFG flag to be 1, I fill the TXBUF with the data to send.
>> I see in IAR that TXBUF now contains the correct data. TXIFG is low indicating the buffer is filled.
>> Now, according to how the USCI module works, the data is supposed to be transferred over to the shift register. This makes the TXBUF free to receive another byte of data, so the TXIFG flag is set. While the Shift register is still shifting the bits out, UCBUSY flag is set and the new data filled in TXBUF will remain there until the shifting is finished.
>> However, in my case, after TXBUF is filled for the first time and TXIFG is false, UCBUSY is not set, therefore the TXBUF never becomes available to take a new byte. TXIFG is therefore never set again.
Here is my setup code
//////////////////////////////////////////
P3SEL = BIT1 | BIT3; // Route pins to USCI_A for SPI
// P7.1 - UCA0MOSI // SPI mode 0 needs CPOL=CKPL=0, CPHA=0 -> CKPH=1; msb first, master,
// P7.2 - UCA0MISO // 8 bit (default), 3-wire (default, mode 0), synchronous
// P7.3 - UCA0CLK
UCA0CTL0 = UCCKPH | UCCKPL | UCMSB | UCMST | UCMODE_0 | UCSYNC; // sunchronous mode
UCA0CTL1 = UCSSEL1 | UCSWRST; // Clock from SMCLK; hold in reset
UCA0BR1 = 0; // Upper byte of divider word
UCA0BR0 = 10; // Clock = SMCLK / 10 = 100kHz
UCA0CTL1 &= ~UCSWRST; // Release from reset
This is where I am checking the TXIFG buffer
/////////////////////////////////////////////////////////////////////////////////
void oled_Data(unsigned char Data)
{
char rx;
OLED_SET_DATA(); // Set DC, RW, nRES pins as necessary
// Data mode needs to be set before the buffer can be written to, because the buffer will
// move its content to the SR which will starting pushing bits out immediately
if(IFG2_bit.UCA0RXIFG) rx = UCA0RXBUF;
while(IFG2_bit.UCA0TXIFG!=1){}
DPORT_OUT = Data; // Data to be written to the display
OLED_udelay(100); // Delay for 100 us
OLED_udelay(100); // Delay for 100 us
}
I would appreciate any help on this! Thank you!
