geolover
Joined: 08 Feb 2011
Posts: 18
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| USB CDC problem |
 Posted: Tue Mar 22, 2011 3:39 pm |
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Hello! I had successfully implemented an USB CDC with 18F4550 to retrieve data from a PIC24FJ by using a SPI interface, however, between each operation, at least 100us delay must be added to ensure the data sent by PIC24FJ does not get corrupted....
I think the problem lies with the use of #use delay() because for PIC18F I'm using a 20MHz crystal to Operate at 48MHz, in PIC24FJ however I set #use delay() to 8MHz....
| Code: |
#include <18F4550.h>
//configure a 20MHz crystal to operate at 48MHz
#fuses HSPLL,NOWDT,NOPROTECT,NOLVP,NODEBUG,USBDIV,PLL5,CPUDIV1,VREGEN
//#fuses USBDIV, PLL1, CPUDIV1, PROTECT, NOCPD, noBROWNOUT,HSPLL,NOWDT,nolvp, VREGEN
#use delay(clock=48000000)
/////////////////////////////////////////////////////////////////////////////
//
// If you are using a USB connection sense pin, define it here. If you are
// not using connection sense, comment out this line. Without connection
// sense you will not know if the device gets disconnected.
// (connection sense should look like this:
// 100k
// VBUS-----+----/\/\/\/\/\----- (I/O PIN ON PIC)
// |
// +----/\/\/\/\/\-----GND
// 100k
// (where VBUS is pin1 of the USB connector)
//
/////////////////////////////////////////////////////////////////////////////
///only the 18F4550 development kit has this pin
// Includes all USB code and interrupts, as well as the CDC API
#include <usb_cdc.h>
#rom int 0xf00000={1,2,3,4}
void main() {
int i;
int8 value0[1024], value1[1024],value2[1024];
setup_spi(spi_slave | spi_ss_disabled);
// setup_spi (SPI_MASTER | SPI_H_TO_L | SPI_CLK_DIV_4);
usb_cdc_init();
usb_init();
while(!usb_cdc_connected()) {}
do {
usb_task();
if (usb_enumerated()) {
// printf(usb_cdc_putc, "\r\n\nData read from ADC:\r\n"); // Display contents of the first 64
if (spi_data_is_in())
{
// while(!spi_data_is_in()); // wait for SPI activity from master
// Read byre from SPI interface
for (i=0;i<1024;i++)
{
value0[i] = spi_read();
value1[i] = spi_read();
value2[i] = spi_read();
}
// for (i=0;i<256;i++)
// {
// printf(usb_cdc_putc, "%2x ", i);
// }
for (j=0;i<1024;j++)
{
// Write byte to USB
printf(usb_cdc_putc, "%X%X%X\r",value0[i],value1[i],value2[i]);
}
}
}
}while (TRUE);
}
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| Code: | #FUSES NOWDT //No Watch Dog Timer
#FUSES NOJTAG //JTAG disabled
#FUSES NOPROTECT //Code not protected from reading
#FUSES NOWRT //Program memory not write protected
#FUSES NODEBUG //No Debug mode for ICD
#FUSES NOCOE //Device will reset into operational mode
#FUSES NOIESO //Internal External Switch Over mode disabled
#FUSES PR //Primary Oscillator
//#FUSES PR_PLL //Primary Oscillator with PLL
#FUSES CKSNOFSM //Clock Switching is enabled, fail Safe clock monitor is disabled
#FUSES NOOSCIO //OSC2 is clock output
#FUSES XT
#use delay(clock=8000000)
#use rs232(UART1,baud=9600,parity=N,bits=8)
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