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USB-Serial.ino
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USB-Serial.ino
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/*
Copyright (c) 2014-2015 NicoHood
See the readme for credit to other people.
USB-Serial
Transferes from USB to HW Serial and vice versa.
It also resets the main MCU on a DTR rise.
Keep in mind that HoodLoader2 in bootloader mode
supports faster USART speeds (2M full duplex)
and that this us just an example how to reproduce
a simple USB-Serial converter.
Reset pin u2 Series: 20
Reset pin 32u4 with HoodLoader2: 4
*/
// Refine the reset pin to reset the destination MCU.
// This definition by default is equal to the HoodLoader2 used reset pin.
// But you still can use another pin for your layout.
const uint8_t resetPin = IO_MCU_RESET_PIN;
void setup()
{
// Set main MCU by default active
digitalWrite(resetPin, HIGH);
pinMode(resetPin, OUTPUT);
// Start USB Serial
Serial.begin(0);
}
void loop()
{
// Check if the USB virtual serial wants a new baud rate
static uint32_t baud = 0;
if (Serial.baud() != baud) {
baud = Serial.baud();
Serial1.end();
if (baud)
Serial1.begin(baud);
}
// reset the main mcu if DTR goes HIGH
if (Serial.dtr())
digitalWrite(resetPin, LOW);
else
digitalWrite(resetPin, HIGH);
// Serial -> USB
// Check if any data has arrived on the USART serial port
// and USB is ready for the next bytes
int readAvailable = Serial1.available();
if (readAvailable > 0) {
int writeAvailable = Serial.availableForWrite();
if (writeAvailable > 0) {
// Write maximum one EP_SIZE to not block with Zero Length packets
uint8_t buff[USB_EP_SIZE - 1];
if (readAvailable > sizeof(buff))
readAvailable = sizeof(buff);
// Dont write more than USB can take to not block
if (readAvailable > writeAvailable)
readAvailable = writeAvailable;
// Read data from the hardware serial port
int n = Serial1.readBytes((char *)buff, readAvailable);
// Write it to the USB port
Serial.write(buff, n);
}
}
// USB -> Serial
// Check if any data has arrived on the USB virtual serial port
// and USART is ready for the next bytes
readAvailable = Serial.available();
if (readAvailable > 0) {
int writeAvailable = Serial1.availableForWrite();
if (writeAvailable > 0) {
// Write maximum one EP_SIZE to not block with Zero Length packets
if (readAvailable > (USB_EP_SIZE - 1))
readAvailable = (USB_EP_SIZE - 1);
// Dont write more than USART buffer is free to not block
if (readAvailable > writeAvailable)
readAvailable = writeAvailable;
// Read data from the USB serial port
uint8_t buff[SERIAL_TX_BUFFER_SIZE];
int n = Serial.readBytes((char *)buff, readAvailable);
// Write it to the USART port
Serial1.write(buff, n);
}
}
}