From 468f199d22ee6825973088014b74dd9b7e3d6e83 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Thu, 11 Mar 2021 10:53:02 +0100
Subject: [PATCH] application: add multiplexer control

---
 application.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/application.c b/application.c
index 3446fff..f062e93 100644
--- a/application.c
+++ b/application.c
@@ -59,6 +59,12 @@ const uint8_t channels[] = {ADC_CHANNEL17, ADC_CHANNEL(TARGET_CHANNEL), ADC_CHAN
 #define SIGNAL_PU_PIN PA4 /**< pin to pull signal to target voltage (controlling gate of pMOS) */
 #define TARGET_EN PA5 /**< pin to provide target voltage to LV side of voltage shifter (pulling them high through 10 kO) */
 
+#define MUX_EN_PIN PB2 /**< pin to enable analog multiplexer (active low) */
+#define MUX_S0_PIN PA6 /**< pin to set S0 bit of analog multiplexer */
+#define MUX_S1_PIN PA7 /**< pin to set S1 bit of analog multiplexer */
+#define MUX_S2_PIN PB0 /**< pin to set S2 bit of analog multiplexer */
+#define MUX_S3_PIN PB1 /**< pin to set S3 bit of analog multiplexer */
+
 size_t putc(char c)
 {
 	size_t length = 0; // number of characters printed
@@ -118,6 +124,39 @@ static float* measure_voltages(void)
 	return voltages;
 }
 
+/** select channel of multiplexer
+ *  @param[in] channel channel to select, or -1 to disable multiplexer
+ */
+static void mux_select(int8_t channel)
+{
+	gpio_set(GPIO_PORT(MUX_EN_PIN), GPIO_PIN(MUX_EN_PIN)); // disable multiplexer while we are switching
+	if (channel < 0 || channel > 15) {
+		return; // no channel to select
+	}
+	// select channel using bit pattern
+	if (channel & 0x1) {
+		gpio_set(GPIO_PORT(MUX_S0_PIN), GPIO_PIN(MUX_S0_PIN));
+	} else {
+		gpio_clear(GPIO_PORT(MUX_S0_PIN), GPIO_PIN(MUX_S0_PIN));
+	}
+	if (channel & 0x2) {
+		gpio_set(GPIO_PORT(MUX_S1_PIN), GPIO_PIN(MUX_S1_PIN));
+	} else {
+		gpio_clear(GPIO_PORT(MUX_S1_PIN), GPIO_PIN(MUX_S1_PIN));
+	}
+	if (channel & 0x4) {
+		gpio_set(GPIO_PORT(MUX_S2_PIN), GPIO_PIN(MUX_S2_PIN));
+	} else {
+		gpio_clear(GPIO_PORT(MUX_S2_PIN), GPIO_PIN(MUX_S2_PIN));
+	}
+	if (channel & 0x8) {
+		gpio_set(GPIO_PORT(MUX_S3_PIN), GPIO_PIN(MUX_S3_PIN));
+	} else {
+		gpio_clear(GPIO_PORT(MUX_S3_PIN), GPIO_PIN(MUX_S3_PIN));
+	}
+	gpio_clear(GPIO_PORT(MUX_EN_PIN), GPIO_PIN(MUX_EN_PIN)); // enable multiplexer
+}
+
 // menu commands
 
 static void command_swd_scan(void* argument)
@@ -578,6 +617,30 @@ void main(void)
 	gpio_mode_setup(GPIO_PORT(SIGNAL_PU_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(SIGNAL_PU_PIN)); // configure pin as output
 	puts("OK\n");
 
+	puts("setup analog multiplexer: ");
+	rcc_periph_clock_enable(GPIO_RCC(MUX_EN_PIN)); // enable clock for port domain
+	gpio_set(GPIO_PORT(MUX_EN_PIN), GPIO_PIN(MUX_EN_PIN)); // ensure multiplexer is disabled
+	gpio_set_output_options(GPIO_PORT(MUX_EN_PIN), GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, GPIO_PIN(MUX_EN_PIN)); // set output as push-pull to drive correctly
+	gpio_mode_setup(GPIO_PORT(MUX_EN_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(MUX_EN_PIN)); // configure pin as output
+	rcc_periph_clock_enable(GPIO_RCC(MUX_S0_PIN)); // enable clock for port domain
+	gpio_clear(GPIO_PORT(MUX_S0_PIN), GPIO_PIN(MUX_S0_PIN)); // any channel selected is fine
+	gpio_set_output_options(GPIO_PORT(MUX_S0_PIN), GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, GPIO_PIN(MUX_S0_PIN)); // set output as push-pull to drive correctly
+	gpio_mode_setup(GPIO_PORT(MUX_S0_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(MUX_S0_PIN)); // configure pin as output
+	rcc_periph_clock_enable(GPIO_RCC(MUX_S1_PIN)); // enable clock for port domain
+	gpio_clear(GPIO_PORT(MUX_S1_PIN), GPIO_PIN(MUX_S1_PIN)); // any channel selected is fine
+	gpio_set_output_options(GPIO_PORT(MUX_S1_PIN), GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, GPIO_PIN(MUX_S1_PIN)); // set output as push-pull to drive correctly
+	gpio_mode_setup(GPIO_PORT(MUX_S1_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(MUX_S1_PIN)); // configure pin as output
+	rcc_periph_clock_enable(GPIO_RCC(MUX_S2_PIN)); // enable clock for port domain
+	gpio_clear(GPIO_PORT(MUX_S2_PIN), GPIO_PIN(MUX_S2_PIN)); // any channel selected is fine
+	gpio_set_output_options(GPIO_PORT(MUX_S2_PIN), GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, GPIO_PIN(MUX_S2_PIN)); // set output as push-pull to drive correctly
+	gpio_mode_setup(GPIO_PORT(MUX_S2_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(MUX_S2_PIN)); // configure pin as output
+	rcc_periph_clock_enable(GPIO_RCC(MUX_S3_PIN)); // enable clock for port domain
+	gpio_clear(GPIO_PORT(MUX_S3_PIN), GPIO_PIN(MUX_S3_PIN)); // any channel selected is fine
+	gpio_set_output_options(GPIO_PORT(MUX_S3_PIN), GPIO_OTYPE_PP, GPIO_OSPEED_2MHZ, GPIO_PIN(MUX_S3_PIN)); // set output as push-pull to drive correctly
+	gpio_mode_setup(GPIO_PORT(MUX_S3_PIN), GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO_PIN(MUX_S3_PIN)); // configure pin as output
+	mux_select(-1); // ensure it is disabled
+	puts("OK\n");
+
 	puts("setup ADC to measure voltages: ");
 	rcc_periph_clock_enable(RCC_ADC1); // enable clock for ADC domain
 	adc_power_off(ADC1); // switch off ADC while configuring it