From 423a0ec90b3ff0b616e376d2d5977033dd7c9a8e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Wed, 24 Mar 2021 00:54:53 +0100
Subject: [PATCH] application: add command to identify I/O channels

---
 application.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/application.c b/application.c
index fb863ee..3c7eebd 100644
--- a/application.c
+++ b/application.c
@@ -301,6 +301,91 @@ static void command_target_reset(void* argument)
 	}
 }
 
+/** identify if signal is an input or output
+ *  @param[in] argument no argument required
+ */
+static void command_types(void* argument)
+{
+	(void)argument; // we won't use the argument
+	command_target_voltage(NULL); // print target voltage (also sets measurement conditions)
+	float* voltages = measure_voltages(); // measure voltages
+	if (voltages[1] < 0.5) { // check target voltage connection
+		puts("connect target voltage to test channel type\n");
+		return;
+	}
+
+	puts("signal voltage  pulled  pull-up pulled pull-down signal\n");
+	puts(" name  raw (V) down (V) (kOhm)  up (V)  (kOhm)    type \n");
+
+	// just to be sure, reset measurement conditions
+	gpio_set(GPIO_PORT(SIGNAL_PD_PIN), GPIO_PIN(SIGNAL_PD_PIN)); // ensure pull-down is not active
+	gpio_set(GPIO_PORT(SIGNAL_PU_PIN), GPIO_PIN(SIGNAL_PU_PIN)); // ensure pull-up is not active
+
+	for (uint8_t i = channel_start; i <= channel_stop; i++) {
+		printf("CH%02u", i);
+		puts("    ");
+		mux_select(i); // select the channel
+		voltages = measure_voltages(); // measure raw voltages
+		print_fpu(voltages[2], 2);
+		const float raw = voltages[2]; // remember un-pulled voltage
+		puts("    ");
+
+		gpio_clear(GPIO_PORT(SIGNAL_PD_PIN), GPIO_PIN(SIGNAL_PD_PIN)); // pull down signal
+		sleep_us(10); // wait a tiny bit for voltage to settle
+		voltages = measure_voltages(); // measure pulled down voltages
+		gpio_set(GPIO_PORT(SIGNAL_PD_PIN), GPIO_PIN(SIGNAL_PD_PIN)); // remove pull-down
+		voltages[2] *= 2.0; // pulling creates a voltage divider (to ground)
+		const bool low = (voltages[2] < 0.5); // remember if we were able to pull it down
+		const float pullup = (2000.0 * (raw - voltages[2]) / voltages[2]) / 1000.0; // estimate external pull-up
+		print_fpu(voltages[2], 2);
+		puts("     ");
+		if (pullup > 100.0) {
+			puts(">100");
+		} else if (pullup < 1.0) {
+			puts(" <1 ");
+		} else {
+			printf(" %02u ", (uint32_t)round(pullup));
+		}
+		puts("    ");
+
+		gpio_clear(GPIO_PORT(SIGNAL_PU_PIN), GPIO_PIN(SIGNAL_PU_PIN)); // pull up signal
+		sleep_us(10); // wait a tiny bit for voltage to settle
+		voltages = measure_voltages(); // measure pulled up voltages
+		gpio_set(GPIO_PORT(SIGNAL_PU_PIN), GPIO_PIN(SIGNAL_PU_PIN)); // remove pull-up
+		voltages[2] = voltages[2] *  2.0 - voltages[1]; // pulling creates a voltage divider (to target)
+		const bool high = (voltages[2] > 3.2 || voltages[2] > voltages[1] * 0.5); // remember if we were able to pull it up
+		const float pulldown = (2000.0 * voltages[2] / (voltages[1] - voltages[2])) / 1000.0; // estimate external pull-down
+		print_fpu(voltages[2], 2);
+		puts("    ");
+		if (pulldown > 100.0) {
+			puts(">100");
+		} else if (pulldown < 1.0) {
+			puts(" <1 ");
+		} else {
+			printf(" %02u ", (uint32_t)round(pulldown));
+		}
+		puts("    ");
+
+		if (low && high) {
+			if (pullup > 1.0 && pullup < 100.0 && (pulldown < 1.0 || pulldown > 100.0)) {
+				puts("pulled-up");
+			} else if (pulldown > 1.0 && pulldown < 100.0 && (pullup < 1.0 || pullup > 100.0)) {
+				puts("pulled-down");
+			} else {
+				puts("floating");
+			}
+		} else if (low) {
+			puts("low");
+		} else if (high) {
+			puts("high");
+		} else {
+			puts("unknown");
+		}
+		putc('\n');
+	}
+	mux_select(-1); // disable multiplexer
+}
+
 /** set first channel of range to scan
  *  @param[in] argument optional pointer to first channel number
  */
@@ -596,6 +681,14 @@ static const struct menu_command_t menu_commands[] = {
 		.argument_description = "[0|1|ODL|ODH|PPL|PPH]",
 		.command_handler = &command_target_reset,
 	},
+	{
+		.shortcut = 't',
+		.name = "type",
+		.command_description = "identify signal types",
+		.argument = MENU_ARGUMENT_NONE,
+		.argument_description = NULL,
+		.command_handler = &command_types,
+	},
 	{
 		.shortcut = 'c',
 		.name = "start",