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#include <xc.h>
#include <stdbool.h>
#include <stdint.h>
#include <usb.h>
#include <usb_device.h>
#include <usb_device_cdc.h>
#include "usb.h"
// Line coding
// See struct USB_CDC_LINE_CODING
enum {
DATA_RATE = 9600, // bps
CHAR_FORMAT = NUM_STOP_BITS_1,
PARITY_TYPE = PARITY_NONE,
DATA_BITS = 8,
};
// State
typedef enum {
IDLE, // waiting for command
CMD_START, // received opcode
ECHO,
WRITE_EEPROM,
READ_EEPROM,
} State;
static uint8_t readBuf[CDC_DATA_OUT_EP_SIZE];
static uint8_t writeBuf[CDC_DATA_IN_EP_SIZE];
static State state = IDLE;
// Handle "e" echo command.
static void
echo(void) {
static uint8_t readLen = 0u;
static uint8_t ri, wi;
if (!USBUSARTIsTxTrfReady()) {
return;
}
if (readLen == 0u) {
readLen = getsUSBUSART(readBuf, sizeof(readBuf));
ri = 0u;
wi = 0u;
}
while (readLen--) {
if (wi > sizeof(writeBuf)) {
// Overflow; flush
putUSBUSART(writeBuf, sizeof(writeBuf));
wi = 0u;
return; // continue on next call
}
writeBuf[wi] = readBuf[ri];
if (readBuf[ri] == '\n') {
// End of command
putUSBUSART(writeBuf, wi);
readLen = 0u;
state = IDLE;
return;
}
ri++;
wi++;
}
}
// Handle "w" write eeprom command.
static void
writeEeprom(void) {
// TODO
}
// Handle "r" read eeprom command.
static void readEeprom(void) {
// TODO
}
static void
setCmdState(uint8_t opcode) {
switch (opcode) {
case 'e': // echo
state = ECHO;
break;
case 'w':
state = WRITE_EEPROM;
break;
case 'r':
state = READ_EEPROM;
break;
}
}
void
usbTask(void) {
static uint8_t opcode = 0u;
USBDeviceTasks();
if (USBGetDeviceState() < CONFIGURED_STATE) {
return;
}
if (USBIsDeviceSuspended()) {
return;
}
switch (state) {
case IDLE:
if (getsUSBUSART(&opcode, 1u) > 0) {
state = CMD_START;
}
break;
case CMD_START:
// Skip space char
if (getsUSBUSART(readBuf, 1u) > 0) {
setCmdState(opcode);
}
case ECHO: echo();
break;
case WRITE_EEPROM: writeEeprom();
break;
case READ_EEPROM: readEeprom();
break;
}
CDCTxService();
}
static void
configure(void) {
line_coding.dwDTERate = DATA_RATE;
line_coding.bCharFormat = CHAR_FORMAT;
line_coding.bParityType = PARITY_TYPE;
line_coding.bDataBits = DATA_BITS;
}
bool
USER_USB_CALLBACK_EVENT_HANDLER(USB_EVENT event, void *pdata, uint16_t size) {
switch ((int)event) {
case EVENT_TRANSFER:
break;
case EVENT_SOF:
break;
case EVENT_SUSPEND:
break;
case EVENT_RESUME:
break;
case EVENT_CONFIGURED:
CDCInitEP();
configure();
break;
case EVENT_SET_DESCRIPTOR:
break;
case EVENT_EP0_REQUEST:
USBCheckCDCRequest();
break;
case EVENT_BUS_ERROR:
break;
case EVENT_TRANSFER_TERMINATED:
break;
default:
break;
}
return true;
}
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