OK, I have it working now!
I changed my platfomio.ini to this:
[env:pico]
;platform = raspberrypi
platform = https://github.com/maxgerhardt/platform-raspberrypi.git
board = pico
framework = arduino
board_build.core = earlephilhower
board_build.filesystem_size = 0.5m
platform_packages =
maxgerhardt/framework-arduinopico@https://github.com/earlephilhower/arduino-pico.git#master
And the demo code in main.cpp looks like this:
#include <Arduino.h>
void setup() {
pinMode(LED_BUILTIN, OUTPUT);
Serial1.setRX(17u);
Serial1.setTX(16u);
Serial1.begin(19200);
}
void loop() {
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(1000); // wait for a second
Serial1.println("Hello World!");
}