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#include <xc.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.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,
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 uint8_t readLen = 0u;
// Handle "e" echo command.
// Returns the next state.
static State
echo(void) {
uint8_t i;
State state = ECHO;
if (readLen == 0u) {
readLen = getsUSBUSART(readBuf, sizeof(readBuf));
}
for (i = 0u; i < readLen; i++) {
writeBuf[i] = readBuf[i];
if (readBuf[i] == '\n') {
// End of command
state = IDLE;
i++;
break;
}
}
if (readLen > 0u) {
putUSBUSART(writeBuf, i);
}
readLen = 0u;
return state;
}
// Handle "w" write eeprom command.
// Returns the next state.
static State
writeEeprom(void) {
// TODO
return IDLE;
}
// Handle "r" read eeprom command.
// Returns the next state.
static State
readEeprom(void) {
// TODO
return IDLE;
}
static State
cmdState(uint8_t opcode) {
switch (opcode) {
case 'e': return ECHO;
case 'w': return WRITE_EEPROM;
case 'r': return READ_EEPROM;
default: return IDLE; // invalid command
}
}
// Read (the start of) a command from USB.
// Leaves <args> at the beginning of the read buffer.
// Returns the next state based on the opcode of the command.
static State
readCmd(void) {
uint8_t opcode;
readLen = getsUSBUSART(readBuf, sizeof(readBuf));
if (readLen < 2u) {
// Invalid command. Must start with <opcode> <space>
return IDLE;
}
opcode = readBuf[0u];
// skip <opcode> <space>
memmove(readBuf, readBuf+2u, readLen-2u);
readLen -= 2u;
return cmdState(opcode);
}
void
usbTask(void) {
static State state = IDLE;
USBDeviceTasks();
if (USBGetDeviceState() < CONFIGURED_STATE) {
return;
}
if (USBIsDeviceSuspended()) {
return;
}
if (USBUSARTIsTxTrfReady()) {
switch (state) {
case IDLE: state = readCmd(); break;
case ECHO: state = echo(); break;
case WRITE_EEPROM: state = writeEeprom(); break;
case READ_EEPROM: state = 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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