Add code to talk with the external RTC chip.

11 files changed, 406 insertions, 4 deletions

diff --git a/.gitignore b/.gitignore
index ad98d14..b8b0ae3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@
 *.hex
 *.lst
 *.map
+*~
diff --git a/Makefile b/Makefile
index 42bd054..43cc10b 100644
--- a/Makefile
+++ b/Makefile
@@ -52,6 +52,7 @@ export BOARD_OBJS = \
 	$(TOPLEVEL)/stm-init.o \
 	$(TOPLEVEL)/stm-fmc.o \
 	$(TOPLEVEL)/stm-uart.o \
+	$(TOPLEVEL)/stm-rtc.o \
 	$(TOPLEVEL)/syscalls.o \
 	$(BOARD_DIR)/TOOLCHAIN_GCC_ARM/startup_stm32f429xx.o \
 	$(BOARD_DIR)/system_stm32f4xx.o \
@@ -127,7 +128,7 @@ hsm: $(BOARD_OBJS) $(LIBS) $(LIBHAL_DIR)/libhal.a
 # don't automatically delete objects, to avoid a lot of unnecessary rebuilding
 .SECONDARY: $(BOARD_OBJS)
 
-.PHONY: board-test rtos-test libhal-test
+.PHONY: board-test rtos-test libhal-test cli-test
 
 clean:
 	rm -f $(BOARD_OBJS)
diff --git a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_conf.h b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_conf.h
index 437ba0d..31c0e31 100644
--- a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_conf.h
+++ b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_conf.h
@@ -68,7 +68,7 @@
 //#define HAL_SDRAM_MODULE_ENABLED
 //#define HAL_HASH_MODULE_ENABLED
 #define HAL_GPIO_MODULE_ENABLED
-//#define HAL_I2C_MODULE_ENABLED
+#define HAL_I2C_MODULE_ENABLED
 //#define HAL_I2S_MODULE_ENABLED
 //#define HAL_IWDG_MODULE_ENABLED
 //#define HAL_LTDC_MODULE_ENABLED
diff --git a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_msp.c b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_msp.c
index 81f2367..a430c5e 100644
--- a/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_msp.c
+++ b/libraries/mbed/targets/cmsis/TARGET_STM/TARGET_STM32F4/TARGET_CRYPTECH_ALPHA/stm32f4xx_hal_msp.c
@@ -47,7 +47,7 @@ void HAL_MspInit(void)
 
   /* USER CODE END MspInit 0 */
 
-  /* XXX 
+  /* XXX
    * Fredrik's HAL_MspInit sets this to NVIC_PRIORITYGROUP_4 (as just
    * happened in HAL_Init), but then he resets it to NVIC_PRIORITYGROUP_0
    * in stm_init. */
@@ -177,4 +177,37 @@ void HAL_UART_MspDeInit(UART_HandleTypeDef* huart)
   }
 }
 
+void HAL_I2C_MspInit(I2C_HandleTypeDef* hi2c)
+{
+    GPIO_InitTypeDef GPIO_InitStruct;
+    if (hi2c->Instance == I2C2) {
+	/*
+	 * I2C2 GPIO Configuration
+	 * PH5     ------> I2C2_SDA
+	 * PH4     ------> I2C2_SCL
+	*/
+	__GPIOH_CLK_ENABLE();
+
+	GPIO_InitStruct.Pin = GPIO_PIN_4 | GPIO_PIN_5;
+	GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
+	GPIO_InitStruct.Pull = GPIO_PULLUP;
+	GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
+	GPIO_InitStruct.Alternate = GPIO_AF4_I2C2;
+	HAL_GPIO_Init(GPIOH, &GPIO_InitStruct);
+
+	/* Peripheral clock enable */
+	__I2C2_CLK_ENABLE();
+    }
+
+}
+
+void HAL_I2C_MspDeInit(I2C_HandleTypeDef* hi2c)
+{
+    if(hi2c->Instance == I2C2) {
+	__I2C2_CLK_DISABLE();
+	HAL_GPIO_DeInit(GPIOH, GPIO_PIN_4 | GPIO_PIN_5);
+    }
+}
+
+
 /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
diff --git a/projects/board-test/Makefile b/projects/board-test/Makefile
index a4a0a70..9b1812f 100644
--- a/projects/board-test/Makefile
+++ b/projects/board-test/Makefile
@@ -1,4 +1,4 @@
-TEST = led-test short-test uart-test fmc-test fmc-perf fmc-probe
+TEST = led-test short-test uart-test fmc-test fmc-perf fmc-probe rtc-test
 
 all: $(TEST:=.elf)
 
diff --git a/projects/board-test/rtc-test.c b/projects/board-test/rtc-test.c
new file mode 100644
index 0000000..b8a7511
--- /dev/null
+++ b/projects/board-test/rtc-test.c
@@ -0,0 +1,161 @@
+/*
+ * Test code for the RTC.
+ *
+ * Dumps the SRAM and EEPROM on startup, then enables the oscillator.
+ * After that, the clock registers are read once a second - the first byte
+ * is seconds (and some control bits, so dont expect 0..59).
+ *
+ */
+#include <string.h>
+
+#include "stm32f4xx_hal.h"
+#include "stm-init.h"
+#include "stm-led.h"
+#include "stm-uart.h"
+#include "stm-rtc.h"
+
+#define DELAY() HAL_Delay(1000)
+
+
+uint8_t buf[1024];
+uint32_t i;
+
+
+uint32_t device_ready(uint16_t i2c_addr)
+{
+    uart_send_string2(STM_UART_MGMT, "Checking readiness of 0x");
+    uart_send_number2(STM_UART_MGMT, i2c_addr, 4, 16);
+    uart_send_string2(STM_UART_MGMT, "...");
+
+    if (rtc_device_ready(i2c_addr) == HAL_OK) {
+	uart_send_string2(STM_UART_MGMT, "OK\r\n");
+	return 1;
+    }
+
+    uart_send_string2(STM_UART_MGMT, "Not ready (0x");
+    uart_send_number2(STM_UART_MGMT, i, 4, 16);
+    uart_send_string2(STM_UART_MGMT, ")\r\n");
+
+    return 0;
+}
+
+
+void send_byte(const uint16_t i2c_addr, const uint8_t value)
+{
+    uint8_t ch = value;
+
+    uart_send_string2(STM_UART_MGMT, "Sending ");
+    uart_send_number2(STM_UART_MGMT, ch, 2, 16);
+    uart_send_string2(STM_UART_MGMT, " to 0x");
+    uart_send_number2(STM_UART_MGMT, i2c_addr, 4, 16);
+    uart_send_string2(STM_UART_MGMT, "...");
+
+    if (rtc_send_byte(i2c_addr, ch, 1000) != HAL_OK) {
+	uart_send_string2(STM_UART_MGMT, "Timeout\r\n");
+	Error_Handler();
+    }
+
+    uart_send_string2(STM_UART_MGMT, "OK\r\n");
+}
+
+void read_bytes (uint8_t *buf, const uint16_t i2c_addr, const uint8_t len)
+{
+    uart_send_string2(STM_UART_MGMT, "Reading ");
+    uart_send_number2(STM_UART_MGMT, len, 3, 10);
+    uart_send_string2(STM_UART_MGMT, " bytes from 0x");
+    uart_send_number2(STM_UART_MGMT, i2c_addr, 4, 16);
+    uart_send_string2(STM_UART_MGMT, "...");
+
+    if (rtc_read_bytes(i2c_addr, buf, len, 1000) != HAL_OK) {
+	uart_send_string2(STM_UART_MGMT, "Timeout\r\n");
+	Error_Handler();
+    }
+
+    uart_send_string2(STM_UART_MGMT, "OK\r\n");
+}
+
+void request_data(uint8_t *buf, const uint16_t i2c_addr, const uint8_t offset, const uint8_t bytes)
+{
+    send_byte(i2c_addr, offset);
+    read_bytes(buf, i2c_addr, bytes);
+}
+
+void print_time()
+{
+    request_data(buf, RTC_RTC_ADDR, RTC_TIME_OFFSET, RTC_TIME_BYTES);
+
+    for (i = 0; i < RTC_TIME_BYTES; i++) {
+	uart_send_number2(STM_UART_MGMT, buf[i], 2, 16);
+	uart_send_string2(STM_UART_MGMT, " ");
+    }
+}
+
+void dump_sram()
+{
+    request_data(buf, RTC_RTC_ADDR, 0x0, RTC_SRAM_TOTAL_BYTES);
+
+    uart_send_string2(STM_UART_MGMT, "SRAM contents:\r\n");
+    uart_send_hexdump(STM_UART_MGMT, buf, 0, RTC_SRAM_TOTAL_BYTES);
+
+    uart_send_string2(STM_UART_MGMT, "\r\n");
+}
+
+void dump_eeprom()
+{
+    request_data(buf, RTC_EEPROM_ADDR, 0x0, RTC_EEPROM_TOTAL_BYTES);
+
+    uart_send_string2(STM_UART_MGMT, "EEPROM contents:\r\n");
+    uart_send_hexdump(STM_UART_MGMT, buf, 0, RTC_EEPROM_TOTAL_BYTES);
+    uart_send_string2(STM_UART_MGMT, "\r\n");
+
+    request_data(buf, RTC_EEPROM_ADDR, RTC_EEPROM_EUI48_OFFSET, RTC_EEPROM_EUI48_BYTES);
+    uart_send_string2(STM_UART_MGMT, "EEPROM EUI-48:\r\n");
+    uart_send_hexdump(STM_UART_MGMT, buf, RTC_EEPROM_EUI48_OFFSET, RTC_EEPROM_EUI48_BYTES);
+
+    uart_send_string2(STM_UART_MGMT, "\r\n");
+}
+
+void enable_oscillator()
+{
+    uart_send_string2(STM_UART_MGMT, "Enabling oscillator...\r\n");
+
+    if (rtc_enable_oscillator() != HAL_OK) {
+	uart_send_string2(STM_UART_MGMT, "Timeout\r\n");
+	Error_Handler();
+    }
+
+    uart_send_string2(STM_UART_MGMT, "OK\r\n");
+}
+
+
+int
+main()
+{
+    stm_init();
+    uart_send_string2(STM_UART_MGMT, "\r\n\r\n*** Init done\r\n");
+
+    dump_sram();
+    dump_eeprom();
+
+    enable_oscillator();
+
+    while (1)  {
+	memset(buf, 0, sizeof(buf));
+
+	if (! device_ready(RTC_RTC_ADDR)) {
+	    goto fail;
+	}
+
+	print_time(buf);
+
+	uart_send_string2(STM_UART_MGMT, "\r\n\r\n");
+
+	HAL_GPIO_TogglePin(LED_PORT, LED_GREEN);
+	DELAY();
+	continue;
+
+    fail:
+	HAL_GPIO_TogglePin(LED_PORT, LED_RED);
+	DELAY();
+    }
+}
diff --git a/stm-init.c b/stm-init.c
index 2219d43..af3d47b 100644
--- a/stm-init.c
+++ b/stm-init.c
@@ -44,6 +44,9 @@
 #ifdef HAL_UART_MODULE_ENABLED
 #include "stm-uart.h"
 #endif
+#ifdef HAL_I2C_MODULE_ENABLED
+#include "stm-rtc.h"
+#endif
 
 /* Private variables ---------------------------------------------------------*/
 
@@ -55,6 +58,9 @@ static void MX_GPIO_Init(void);
 static void MX_USART1_UART_Init(void);
 static void MX_USART2_UART_Init(void);
 #endif
+#ifdef HAL_I2C_MODULE_ENABLED
+static void MX_I2C2_Init(void);
+#endif
 
 void stm_init(void)
 {
@@ -74,6 +80,9 @@ void stm_init(void)
   MX_USART1_UART_Init();
   MX_USART2_UART_Init();
 #endif
+#ifdef HAL_I2C_MODULE_ENABLED
+  MX_I2C2_Init();
+#endif
 }
 
 
@@ -138,6 +147,26 @@ static void MX_GPIO_Init(void)
 }
 #endif
 
+#ifdef HAL_I2C_MODULE_ENABLED
+/* I2C2 init function (external RTC chip) */
+void MX_I2C2_Init(void)
+{
+    hi2c_rtc.Instance = I2C2;
+    hi2c_rtc.Init.ClockSpeed = 10000;
+    hi2c_rtc.Init.DutyCycle = I2C_DUTYCYCLE_2;
+    hi2c_rtc.Init.OwnAddress1 = 0;  /* Will operate as Master */
+    hi2c_rtc.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
+    hi2c_rtc.Init.DualAddressMode = I2C_DUALADDRESS_DISABLED;
+    hi2c_rtc.Init.OwnAddress2 = 0;
+    hi2c_rtc.Init.GeneralCallMode = I2C_GENERALCALL_DISABLED;
+    hi2c_rtc.Init.NoStretchMode = I2C_NOSTRETCH_DISABLED;
+
+    if (HAL_I2C_Init(&hi2c_rtc) != HAL_OK) {
+	Error_Handler();
+    }
+}
+#endif
+
 /**
  * @brief  This function is executed in case of error occurrence.
  * @param  None
diff --git a/stm-rtc.c b/stm-rtc.c
new file mode 100644
index 0000000..85afdf4
--- /dev/null
+++ b/stm-rtc.c
@@ -0,0 +1,89 @@
+/*
+ * stm-rtc.c
+ * ----------
+ * Functions for using the externally connected RTC chip.
+ *
+ * Copyright (c) 2015-2016, NORDUnet A/S All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the NORDUnet nor the names of its contributors may
+ *   be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "stm32f4xx_hal.h"
+#include "stm-rtc.h"
+
+I2C_HandleTypeDef hi2c_rtc;
+
+HAL_StatusTypeDef rtc_device_ready(uint16_t i2c_addr)
+{
+    return HAL_I2C_IsDeviceReady (&hi2c_rtc, i2c_addr, 10, 1000);
+}
+
+HAL_StatusTypeDef rtc_enable_oscillator()
+{
+    uint8_t buf[2];
+    HAL_StatusTypeDef res;
+
+    buf[0] = 0;		/* Offset of RTCSEC */
+    buf[1] = 1 << 7;	/* datasheet REGISTERS 5-1, bit 7 = ST (start oscillator) */
+
+    while (HAL_I2C_Master_Transmit (&hi2c_rtc, RTC_RTC_ADDR_W, buf, 2, 1000) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
+
+HAL_StatusTypeDef rtc_send_byte(const uint16_t i2c_addr, const uint8_t value, const uint16_t timeout)
+{
+    HAL_StatusTypeDef res;
+
+    while (HAL_I2C_Master_Transmit (&hi2c_rtc, i2c_addr, &value, 1, timeout) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
+
+HAL_StatusTypeDef rtc_read_bytes (const uint16_t i2c_addr, uint8_t *buf, const uint8_t len, const uint16_t timeout)
+{
+    HAL_StatusTypeDef res;
+
+    while (HAL_I2C_Master_Receive (&hi2c_rtc, i2c_addr, buf, len, 1000) != HAL_OK) {
+	res = HAL_I2C_GetError (&hi2c_rtc);
+	if (res != HAL_I2C_ERROR_AF) {
+	    return res;
+	}
+    }
+
+    return HAL_OK;
+}
diff --git a/stm-rtc.h b/stm-rtc.h
new file mode 100644
index 0000000..edbed9d
--- /dev/null
+++ b/stm-rtc.h
@@ -0,0 +1,62 @@
+/*
+ * stm-rtc.h
+ * ---------
+ * Functions and defines to use the externally connected RTC chip.
+ *
+ * Copyright (c) 2015-2016, NORDUnet A/S All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the NORDUnet nor the names of its contributors may
+ *   be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __STM32_RTC_H
+#define __STM32_RTC_H
+
+#include "stm32f4xx_hal.h"
+
+extern I2C_HandleTypeDef hi2c_rtc;
+
+extern HAL_StatusTypeDef rtc_device_ready(uint16_t i2c_addr);
+extern HAL_StatusTypeDef rtc_enable_oscillator();
+extern HAL_StatusTypeDef rtc_send_byte(const uint16_t i2c_addr, const uint8_t value, const uint16_t timeout);
+extern HAL_StatusTypeDef rtc_read_bytes (const uint16_t i2c_addr, uint8_t *buf, const uint8_t len, const uint16_t timeout);
+
+#define RTC_RTC_ADDR			0xdf
+#define RTC_EEPROM_ADDR			0xaf
+
+#define RTC_RTC_ADDR_W			RTC_RTC_ADDR ^ 1	/* turn off LSB to write */
+#define RTC_EEPROM_ADDR_W		RTC_EEPROM_ADDR ^ 1	/* turn off LSB to write */
+
+#define RTC_SRAM_TOTAL_BYTES		0x5f
+#define RTC_EEPROM_TOTAL_BYTES		0x7f
+
+#define RTC_EEPROM_EUI48_OFFSET		0xf0
+#define RTC_EEPROM_EUI48_BYTES		8
+
+#define RTC_TIME_OFFSET			0x0  /* Time is at offest 0 in SRAM */
+#define RTC_TIME_BYTES			8
+
+#endif /* __STM32_RTC_H */
diff --git a/stm-uart.c b/stm-uart.c
index 2605f99..6f49ce3 100644
--- a/stm-uart.c
+++ b/stm-uart.c
@@ -165,3 +165,26 @@ HAL_StatusTypeDef uart_send_number2(enum stm_uart_port port, uint32_t num, uint8
 
     return HAL_UART_Transmit(uart, (uint8_t *) where, digits, 0x1);
 }
+
+HAL_StatusTypeDef uart_send_hexdump(enum stm_uart_port port, const uint8_t *buf,
+				    const uint8_t start_offset, const uint8_t end_offset)
+{
+    uint32_t i;
+
+    uart_send_string2(port, "00 -- ");
+
+    for (i = 0; i <= end_offset; i++) {
+	if (i && (! (i % 16))) {
+	    uart_send_string2(port, "\r\n");
+
+	    if (i != end_offset) {
+		/* Output new offset unless the last byte is reached */
+		uart_send_number2(port, i, 2, 16);
+		uart_send_string2(port, " -- ");
+	    }
+	}
+
+	uart_send_number2(port, *(buf + i), 2, 16);
+	uart_send_string2(port, " ");
+    }
+}
diff --git a/stm-uart.h b/stm-uart.h
index 21f3701..e4ee1c3 100644
--- a/stm-uart.h
+++ b/stm-uart.h
@@ -63,6 +63,9 @@ extern HAL_StatusTypeDef uart_send_number2(enum stm_uart_port port, uint32_t num
 extern HAL_StatusTypeDef uart_send_bytes(enum stm_uart_port port, uint8_t *buf, size_t len);
 extern HAL_StatusTypeDef uart_receive_bytes(enum stm_uart_port port, uint8_t *buf, size_t len, uint32_t timeout);
 
+extern HAL_StatusTypeDef uart_send_hexdump(enum stm_uart_port port, const uint8_t *buf,
+					   const uint8_t start_offset, const uint8_t end_offset);
+
 #define uart_send_binary(num, bits)    uart_send_number(num, bits, 2)
 #define uart_send_integer(num, digits) uart_send_number(num, digits, 10)
 #define uart_send_hex(num, digits)     uart_send_number(num, digits, 16)