blob: f704e762a3db0c2b4f26089cd47954cc86ee684d [file] [log] [blame]
// Copyright 2019 The Pigweed Authors
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#include <Arduino.h>
#include <cinttypes>
#include <cstdint>
#include "pw_preprocessor/compiler.h"
#include "pw_sys_io/sys_io.h"
extern "C" void pw_sys_io_arduino_Init() {
// On Linux serial output may still not work if the serial monitor is not
// connected to ttyACM0 quickly enough after reset. This check forces the
// device to wait for a serial connection for up to 3 seconds.
// If you get no serial output, try to connect minicom on the port and then
// reboot the chip (reset button). If using Python miniterm, start it right
// after pushing the reset switch.
while (!Serial && millis() < 3000) {
namespace pw::sys_io {
// Wait for a byte to read on USART1. This blocks until a byte is read. This is
// extremely inefficient as it requires the target to burn CPU cycles polling to
// see if a byte is ready yet.
Status ReadByte(std::byte* dest) {
while (true) {
if (TryReadByte(dest).ok()) {
return OkStatus();
Status TryReadByte(std::byte* dest) {
if (!Serial.available()) {
return Status::Unavailable();
*dest = static_cast<std::byte>(;
return OkStatus();
// Send a byte over the default Arduino Serial port.
Status WriteByte(std::byte b) {
// Serial.write() will block until data can be written.
return OkStatus();
// Writes a string using pw::sys_io, and add newline characters at the end.
StatusWithSize WriteLine(const std::string_view& s) {
size_t chars_written = 0;
StatusWithSize result = WriteBytes(as_bytes(span(s)));
if (!result.ok()) {
return result;
chars_written += result.size();
// Write trailing newline.
result = WriteBytes(as_bytes(span("\r\n", 2)));
chars_written += result.size();
return StatusWithSize(result.status(), chars_written);
} // namespace pw::sys_io