circuitpython/supervisor/serial.h
Jeff Epler 28043c94b5 supervisor: Improve serial connection detection
These changes remove the caveat from supervisor.runtime.serial_connected.

It appears that _tud_cdc_connected() only tracks explicit changes to the
"DTR" bit, which leads to disconnects not being registered.

Instead:
 * when line state is changed explicitly, track the dtr value in
   _serial_connected
 * when the USB bus is suspended, set _serial_connected to False

Testing performed (using sam e54 xplained):  Run a program to show
the state of `serial_connected` on the LED:
```
import digitalio
import supervisor
import board

led = digitalio.DigitalInOut(board.LED)
while True:
    led.switch_to_output(not supervisor.runtime.serial_connected)
```

Try all the following:
 * open, close serial terminal program
    - LED status tracks whether terminal is open
 * turn on/off data lines using the switchable charge-only cable
    - LED turns off when switch is in "charger" position
    - LED turns back on when switch is in Data position and terminal is
      opened (but doesn't turn back on just because switch position is
      changed)
2020-09-17 18:32:06 -05:00

52 lines
1.9 KiB
C

/*
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* The MIT License (MIT)
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* Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
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#ifndef MICROPY_INCLUDED_SUPERVISOR_SERIAL_H
#define MICROPY_INCLUDED_SUPERVISOR_SERIAL_H
#include <stdbool.h>
#include <stdint.h>
#include "py/mpconfig.h"
#ifdef CIRCUITPY_BOOT_OUTPUT_FILE
#include "lib/oofatfs/ff.h"
extern FIL* boot_output_file;
#endif
void serial_early_init(void);
void serial_init(void);
void serial_write(const char* text);
// Only writes up to given length. Does not check for null termination at all.
void serial_write_substring(const char* text, uint32_t length);
char serial_read(void);
bool serial_bytes_available(void);
bool serial_connected(void);
extern volatile bool _serial_connected;
#endif // MICROPY_INCLUDED_SUPERVISOR_SERIAL_H