add mh-z19 test app

# Copyright 2020 Daniel Friesel

#

# SPDX-License-Identifier: CC0-1.0

prompt "MH-Z19C reader"

depends on arch_msp430fr5994lp && !meta_driver_stdin && loop && !wakeup

# vim:ft=make

#

# Copyright 2020 Daniel Friesel

#

# SPDX-License-Identifier: CC0-1.0

ifdef app

	loop = 1

endif

/*

 * Copyright 2021 Daniel Friesel

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#include "arch.h"

#include "driver/gpio.h"

#include "driver/stdout.h"

class SerialOutput : public OutputStream {

	private:

		SerialOutput(const SerialOutput &copy);

	public:

		SerialOutput () {}

		void setup();

		virtual void put(char c) override;

};

/*

 * Baud rate calculation according to datasheet:

 * N := f_{BRCLK} / Baudrate = F_CPU / 115200 in our case

 * if N <= 16: OS16 = 0, UCBR0 = int(N)

 * if N > 16: OS16 = 1, UCBR0 = int(N/16), UCBRF0 = int(((n/16) - int(n/16)) * 16) = int(N)%16

 * Set UCBRS0 according to table 21-4

 */

void SerialOutput::setup()

{

	UCA1CTLW0 |= UCSWRST;

#if F_CPU == 16000000UL

	// 16M / 9600 == 1666.6667 -> UCOS16 = 1, UCBR0 = 104, UCBRF0 = 2, UCBRS0 = 0xd6 ("0.6667")

	UCA1CTLW0 = UCSWRST | UCSSEL__SMCLK;

	UCA1MCTLW = UCOS16 | (2<<4) | 0xd600;

	UCA1BR0 = 104;

#elif F_CPU == 8000000UL

	// 8M / 9600 == 833.3333 -> UCOS16 = 1, UCBR0 = 52, UCBRF0 = 1, UCBRS0 = 0x49 ("0.3335")

	UCA1CTLW0 = UCSWRST | UCSSEL__SMCLK;

	UCA1MCTLW = UCOS16 | (1<<4) | 0x4900;

	UCA1BR0 = 52;

#else

#error Unsupported F_CPU

#endif

	UCA1IRCTL = 0;

	UCA1ABCTL = 0;

	P2REN &= ~(BIT5 | BIT6);

	P2SEL0 &= ~(BIT5 | BIT6);

	P2SEL1 |= BIT5 | BIT6;

	UCA1CTLW0 &= ~UCSWRST;

	//UCA1IE |= UCRXIE;

}

void SerialOutput::put(char c)

{

	while (!(UCA1IFG & UCTXIFG));

	UCA1TXBUF = c;

	if (c == '\n') {

		put('\r');

	}

}

SerialOutput sout;

class SerialInput {

	private:

		SerialInput(const SerialInput &copy);

		char buffer[64];

		volatile unsigned char write_pos, read_pos;

	public:

		SerialInput() : write_pos(0), read_pos(0) {}

		void setup();

		bool hasKey();

		char getKey();

		inline void addKey(char key) {

			buffer[write_pos++] = key;

			write_pos %= 64;

		}

};

void SerialInput::setup()

{

	UCA1IE |= UCRXIE;

}

bool SerialInput::hasKey()

{

	if (write_pos != read_pos) {

		return true;

	}

	return false;

}

char SerialInput::getKey()

{

	char ret = buffer[read_pos++];

	read_pos %= 64;

	return ret;

}

SerialInput sin;

__attribute__((interrupt(USCI_A1_VECTOR))) __attribute__((wakeup)) void handle_stdin()

{

	if (UCA1IFG & UCRXIFG) {

		sin.addKey(UCA1RXBUF);

	}

}

const unsigned char mhz19c_read[] = {0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79};

void loop(void)

{

	static unsigned int interval = 0;

	static char buf[9];

	unsigned char i;

	unsigned int co2_ppm;

	signed int temperature;

	unsigned int unknown_status;

	unsigned int unknown_cal;

	if (interval++ == 2) {

		gpio.led_on(0);

		for (i = 0; i < sizeof(mhz19c_read); i++) {

			sout.put(mhz19c_read[i]);

		}

		arch.sleep_ms(100);

		buf[1] = 0;

		for (i = 0; i < 9; i++) {

			if (sin.hasKey()) {

				buf[i] = sin.getKey();

			} else {

				break;

			}

		}

		if (i == 9) {

			if (buf[0] == 0xff && buf[1] == 0x86) {

				// see https://revspace.nl/MHZ19#Command_0x86_.28read_concentration.29

				co2_ppm = (buf[2] << 8) + buf[3];

				temperature = buf[4] - 40;

				unknown_status = buf[5];

				unknown_cal = (buf[6] << 8) + buf[7];

				kout << "CO₂: " << co2_ppm << " ppm @ " << temperature << " °c     ";

				kout << unknown_status << " / " << unknown_cal << endl;

			} else {

				kout << "! communication error, expected 0xff 0x86, got" << hex << (int)buf[0] << ' ' << (int)buf[1] << dec << endl;

			}

		} else {

			kout << "! timeout" << endl;

		}

		gpio.led_off(0);

		interval = 0;

	}

}

int main(void)

{

	arch.setup();

	gpio.setup();

	kout.setup();

	sout.setup();

	sin.setup();

	arch.idle_loop();

	return 0;

}