From 026562b7d46b14d8846e256d723db5c22e50736e Mon Sep 17 00:00:00 2001
From: Leonardo Celente <leocelente@gmail.com>
Date: Sat, 26 Mar 2022 17:07:11 -0300
Subject: [PATCH] Started driver for state of charge monitor. #24

---
 MAX1720x/max1720x.c | 73 +++++++++++++++++++++++++++++++++++++++++++++
 MAX1720x/max1720x.h | 35 ++++++++++++++++++++++
 2 files changed, 108 insertions(+)
 create mode 100644 MAX1720x/max1720x.c
 create mode 100644 MAX1720x/max1720x.h

diff --git a/MAX1720x/max1720x.c b/MAX1720x/max1720x.c
new file mode 100644
index 0000000..eda4898
--- /dev/null
+++ b/MAX1720x/max1720x.c
@@ -0,0 +1,73 @@
+/*
+ * max17205.c
+ *
+ *  Created on: Mar 20, 2022
+ *      Author: leocelente
+ */
+
+#include <max1720x.h>
+
+/**
+ * Read register
+ */
+static result_uint16_t read(max1720x_t const *max, uint8_t addr) {
+	result_uint16_t result = { 0 };
+	buffer_view_t addr_tr = { .data = &addr, .size = sizeof(addr) };
+	result.hasError |= i2c_transmit(max->dev, addr_tr);
+	uint8_t rx[2] = { 0 };
+	buffer_view_t read_tr = { .data = rx, .size = sizeof(rx) };
+	result.hasError |= i2c_receive(max->dev, read_tr);
+	result.value = (rx[0] << 8) | (rx[1]);
+	return result;
+}
+
+/**
+ * Write register
+ */
+static error_t write(max1720x_t const *max, uint8_t addr, uint16_t value) {
+	uint8_t msb = (value & 0xFF00) >> 8;
+	uint8_t lsb = value;
+	uint8_t data[] = { addr, lsb, msb };
+	buffer_view_t transmission = { .data = data, .size = sizeof(data) };
+	return i2c_transmit(max->dev, transmission);;
+}
+
+/**
+ * Full device reset
+ */
+static void reset(max1720x_t const *max) {
+	write(max, 0x60, 0x00F);
+	delay_ms(50);
+	write(max, 0xBB, 0x001);
+}
+
+error_t max1720x_init(max1720x_t *max) {
+	result_uint16_t ok = read(max, 0x21);
+	if(ok.hasError){
+		return ERROR;
+	}
+
+	if(ok.value != 0x01 || ok.value != 0x05){
+		return ERROR;
+	}
+
+	reset(max);
+	return SUCCESS;
+}
+
+result_max1720x_values_t max1720x_measure(max1720x_t *max) {
+	result_max1720x_values_t out = { .value = { 0 }, .hasError = 0 };
+
+	result_uint16_t result_soc = read(max, 0x06);
+	out.hasError |= result_soc.hasError;
+	out.value.state_of_charge = ((float) result_soc.value) / 256.f;
+
+	result_uint16_t result_cap = read(max, 0x05);
+	out.hasError |= result_cap.hasError;
+	out.value.capacity = ((float) result_cap.value) * 0.005f / 0.01f;
+
+	result_uint16_t result_tte = read(max, 0x11);
+	out.hasError |= result_tte.hasError;
+	out.value.time_to_empty = ((float) result_tte.value) * 5.625f;
+	return out;
+}
diff --git a/MAX1720x/max1720x.h b/MAX1720x/max1720x.h
new file mode 100644
index 0000000..2201207
--- /dev/null
+++ b/MAX1720x/max1720x.h
@@ -0,0 +1,35 @@
+/*
+ * max17205.h
+ *
+ *  Created on: Mar 20, 2022
+ *      Author: leocelente
+ */
+
+#ifndef INC_MAX1720X_H_
+#define INC_MAX1720X_H_
+
+#include "platform/platform.h"
+
+typedef struct {
+  i2c_device_t dev;
+} max1720x_t;
+
+typedef struct {
+  float state_of_charge;
+  float capacity;
+  float time_to_empty;
+} max1720x_values_t;
+
+MAKE_RESULT(max1720x_values_t);
+
+/**
+ *
+ */
+error_t max1720x_init(max1720x_t *max);
+
+/**
+ *
+ */
+result_max1720x_values_t max1720x_measure(max1720x_t *max);
+
+#endif /* INC_MAX1720X_H_ */