From 6509428636047b0c2b533f506a2406e2dc1da9a7 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Wed, 10 Jul 2019 23:52:32 +0200
Subject: [PATCH] A simple IR RC probe

---
 ir-probe/Makefile |   9 ++++
 ir-probe/config.h |   7 +++
 ir-probe/kerm     |   5 ++
 ir-probe/test.c   | 122 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 143 insertions(+)
 create mode 100644 ir-probe/Makefile
 create mode 100644 ir-probe/config.h
 create mode 100644 ir-probe/kerm
 create mode 100644 ir-probe/test.c

diff --git a/ir-probe/Makefile b/ir-probe/Makefile
new file mode 100644
index 0000000..81ed48b
--- /dev/null
+++ b/ir-probe/Makefile
@@ -0,0 +1,9 @@
+ROOT=..
+BINARY=test
+OBJS=test.o
+LIB_OBJS=util-debug.o
+
+WITH_BOOT_LOADER=1
+WITH_DFU_FLASH=1
+
+include $(ROOT)/mk/bluepill.mk
diff --git a/ir-probe/config.h b/ir-probe/config.h
new file mode 100644
index 0000000..2806e8c
--- /dev/null
+++ b/ir-probe/config.h
@@ -0,0 +1,7 @@
+// Processor clock
+
+#define CPU_CLOCK_MHZ 72
+
+// Debug port
+
+#define DEBUG_USART USART1
diff --git a/ir-probe/kerm b/ir-probe/kerm
new file mode 100644
index 0000000..988f567
--- /dev/null
+++ b/ir-probe/kerm
@@ -0,0 +1,5 @@
+set port /dev/ttyUSB0
+set speed 115200
+set flow-control none
+set carrier-watch off
+connect
diff --git a/ir-probe/test.c b/ir-probe/test.c
new file mode 100644
index 0000000..9a2520a
--- /dev/null
+++ b/ir-probe/test.c
@@ -0,0 +1,122 @@
+#include "util.h"
+
+#include <libopencm3/cm3/cortex.h>
+#include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/systick.h>
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+#include <libopencm3/stm32/usart.h>
+
+static void clock_setup(void)
+{
+	rcc_clock_setup_in_hse_8mhz_out_72mhz();
+
+	rcc_periph_clock_enable(RCC_GPIOB);
+	rcc_periph_clock_enable(RCC_GPIOC);
+	rcc_periph_clock_enable(RCC_USART1);
+
+	rcc_periph_reset_pulse(RST_GPIOB);
+	rcc_periph_reset_pulse(RST_GPIOC);
+	rcc_periph_reset_pulse(RST_USART1);
+}
+
+static void gpio_setup(void)
+{
+	// PC13 = BluePill LED
+	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
+	gpio_clear(GPIOC, GPIO13);
+
+	// PB9 = SFH5110 output (5V tolerant)
+	gpio_set_mode(GPIOC, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO9);
+}
+
+static void usart_setup(void)
+{
+	gpio_set_mode(GPIOA, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, GPIO_USART1_TX);
+
+	usart_set_baudrate(USART1, 115200);
+	usart_set_databits(USART1, 8);
+	usart_set_stopbits(USART1, USART_STOPBITS_1);
+	usart_set_mode(USART1, USART_MODE_TX_RX);
+	usart_set_parity(USART1, USART_PARITY_NONE);
+	usart_set_flow_control(USART1, USART_FLOWCONTROL_NONE);
+
+	usart_enable(USART1);
+}
+
+static void tick_setup(void)
+{
+	systick_set_reload(0xffffff);
+	systick_counter_enable();
+	systick_interrupt_disable();
+	systick_clear();
+}
+
+static u16 get_bit(void)
+{
+	return !gpio_get(GPIOB, GPIO9);
+}
+
+#define MAX_SAMPLES 1024
+u32 samples[MAX_SAMPLES];
+
+int main(void)
+{
+	clock_setup();
+	gpio_setup();
+	usart_setup();
+	tick_setup();
+
+	debug_puts("\n\n### Infrared Remote Control receiver ###\n\n");
+
+	for (;;) {
+		gpio_set(GPIOC, GPIO13);
+
+		if (get_bit()) {
+			debug_puts("Waiting for silence\n");
+			while (get_bit())
+				;
+		}
+		debug_puts("Ready...");
+
+		u16 last = 0;
+		uint nsamp = 0;
+		u32 start;
+
+		do {
+			start = systick_get_value();
+			last = get_bit();
+		} while (!last);
+
+		gpio_clear(GPIOC, GPIO13);
+
+		for (;;) {
+			u32 now;
+			u16 curr;
+			uint len;
+			do {
+				now = systick_get_value();
+				len = (start - now) & 0xffffff;
+				if (len > 5000000) {
+					samples[nsamp++] = len;
+					goto timeout;
+				}
+				curr = get_bit();
+			} while (curr == last);
+			samples[nsamp++] = len;
+			if (nsamp >= MAX_SAMPLES)
+				break;
+			start = now;
+			last = curr;
+		}
+
+	timeout:
+		for (uint i=0; i<nsamp; i++) {
+			debug_putc(i ? ' ' : '\n');
+			debug_printf("%u", (samples[i] + CPU_CLOCK_MHZ - 1) / CPU_CLOCK_MHZ);	// in μs
+		}
+		debug_putc('\n');
+	}
+
+	return 0;
+}
-- 
2.39.5