Here is the code I am using to send data to LabVIEW. First I fill a buffer with a long int the with a max value of 16,777,215 because it is a 24-bit ADC. The buffer counts the number of 10millions, millions, 100thousand,...,ones. The LSB value of the buffer is '!' to signal the beginning of the buffer and the MSB value is '0x38' to signal the end of the buffer. The write buffer is then force sent through the UART to LabVIEW.
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/*
dsPIC33FJ256GP710A
note:
union
{
unsigned long ADC_ch_0;
struct
{
unsigned int ADC_ch_0_LSB : 8;
unsigned int ADC_ch_0_lower : 8;
unsigned int ADC_ch_0_middle : 8;
unsigned int ADC_ch_0_upper : 8;
};
} voltage_ch0;
Vch0[read_counter] = voltage_ch0.ADC_ch_0;
*/
case 7:
// Send DATA from buffer to LabVIEW
main_state_machine++; // Go to next state
TX_counter = 1;
DMA2_buffer_WR[0] = '!' // A new serial transmission is starting
hexdec_long(Vch0[write_counter]);
DMA2STA = __builtin_dmaoffset(DMA2_buffer_WR); // Initialize DMA2 buffer address
DMA2CNT = TX_counter; // 10-bit DMA Transfer Count register
DMA2_buffer_WR[TX_counter] = 0x38 // All buffer data has been sent
DMA2CONbits.CHEN = 1; // Enable DMA2 Channel
DMA2REQbits.FORCE = 1; // Force start
break;
case 8:
// Wait for DMA2 transfer to complete...IFS1bits.DMA2IF = 1; //DMA2 Interrupt Flag
break;
case 9:
// Send next DATA
if (write_counter < MAX_BUFF) //MAX_BUFF = 255
{
write_counter++; // increment buffer read counter
main_state_machine -= 2; // Go back 2 steps
}
else main_state_machine++; // Go to next state
break;
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// hexdec_long.c
// Fill DMA2_buffer with Vch0 values
extern char DMA2_buffer_WR[];
extern unsigned char TX_counter;
void hexdec_long(unsigned long count);
char tens;
char ones;
char hundreds;
char thousands;
char thousand10s;
char thousand100s;
char mill;
char mill10s;
void hexdec_long( unsigned long count )
{
mill10s=0;
mill=0;
thousand100s=0;
thousand10s=0;
thousands=0;
hundreds=0;
tens = 0;
ones = 0;
while ( count >= 10000000 )
{
count -= 10000000; // subtract 100000
mill10s++; // increment 10thousands
}
while ( count >= 1000000 )
{
count -= 1000000; // subtract 100000
mill++; // increment 10thousands
}
while ( count >= 100000 )
{
count -= 100000; // subtract 100000
thousand100s++; // increment 10thousands
}
while ( count >= 10000 )
{
count -= 10000; // subtract 10000
thousand10s++; // increment 10thousands
}
while ( count >= 1000 )
{
count -= 1000; // subtract 1000
thousands++; // increment thousands
}
while ( count >= 100 )
{
count -= 100; // subtract 100
hundreds++; // increment hundreds
}
while ( count >= 10 )
{
count -= 10; // subtract 10
tens++; // increment tens
}
ones = count; // remaining count equals ones
DMA2_buffer_WR[TX_counter]=mill10s+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=mill+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=thousand100s+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=thousand10s+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=thousands+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=hundreds+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=tens+0x30;
TX_counter++;
DMA2_buffer_WR[TX_counter]=ones+0x30;
TX_counter++;
}
