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new 95c9525c0d5 boards/arm/stm32f401rc-rs485: Add support to HX711 ADC
95c9525c0d5 is described below
commit 95c9525c0d5d528b146eadd692f4003e796267ff
Author: Rodrigo Sim <rcsi...@gmail.com>
AuthorDate: Tue Jul 8 22:04:23 2025 -0300
boards/arm/stm32f401rc-rs485: Add support to HX711 ADC
This commit adds support for the HX711 ADC in the STM32F401RC-RS485
board and updates the board documentation accordingly.
Signed-off-by: Rodrigo Sim <rcsi...@gmail.com>
---
.../arm/stm32f4/boards/stm32f401rc-rs485/index.rst | 57 +++++++++++
.../arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt | 4 +
boards/arm/stm32/stm32f401rc-rs485/src/Make.defs | 4 +
.../stm32/stm32f401rc-rs485/src/stm32_bringup.c | 10 +-
.../arm/stm32/stm32f401rc-rs485/src/stm32_hx711.c | 104 +++++++++++++++++++++
.../stm32f401rc-rs485/src/stm32f401rc-rs485.h | 21 +++++
6 files changed, 199 insertions(+), 1 deletion(-)
diff --git
a/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
b/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
index 000e07c9f4c..2637b989992 100644
--- a/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
+++ b/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
@@ -943,3 +943,60 @@ NSH usage
4: ( 56, 44) ( 48, 40)
5: ( 70, 55) ( 20, 18)
Test finished
+
+HX711
+-----
+
+HX711 is a precision 24-bit analog-to-digital converter (ADC)
+designed for weigh scales and industrial control applications.
+It interfaces load cells via a simple two-wire serial interface
+(clock and data) and provides high-resolution digital weight
+measurements.
+
+**Enable the following options using ``make menuconfig``:**
+
+::
+
+ CONFIG_ADC=y
+ CONFIG_ANALOG=y
+ CONFIG_ADC_HX711=y
+ CONFIG_EXAMPLES_HX711=y
+
+**Wiring:**
+
+Connect the HX711 to the STM32F4 board using the following pins:
+
++--------+------+
+| HX711 | PIN |
++========+======+
+| SCK | PB1 |
++--------+------+
+| DT | PB2 |
++--------+------+
+
+**NSH usage:**
+
+::
+
+ NuttShell (NSH) NuttX-12.10.0-RC0
+ nsh> hx711 -D
+ Current settings for: /dev/hx711_0
+ average.............: 1
+ channel.............: a
+ gain................: 128
+ value per unit......: 0
+ nsh> hx711 -v 813 -t 10
+ Taring with *float*g precision
+ nsh> hx711 -r 10
+ 11
+ 9
+ 9
+ 10
+ 11
+ 11
+ 11
+ 12
+ 11
+ 10
+
+For more details, refer to the official `HX711 NuttX documentation
<https://nuttx.apache.org/docs/latest/components/drivers/character/analog/adc/hx711/index.html>`_.
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
b/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
index 6348e9cc05c..3bf72325e43 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
@@ -78,6 +78,10 @@ if(CONFIG_VIDEO_FB)
endif()
endif()
+if(CONFIG_ADC_HX711)
+ list(APPEND SRCS stm32_hx711.c)
+endif()
+
target_sources(board PRIVATE ${SRCS})
if(CONFIG_ARCH_CHIP_STM32F401RC)
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
b/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
index 4c5b08a7807..95425aaa474 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
@@ -80,6 +80,10 @@ ifeq ($(CONFIG_DEV_GPIO),y)
CSRCS += stm32_gpio.c
endif
+ifeq ($(CONFIG_ADC_HX711),y)
+CSRCS += stm32_hx711.c
+endif
+
DEPPATH += --dep-path board
VPATH += :board
CFLAGS +=
${INCDIR_PREFIX}$(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)board$(DELIM)board
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
index 98ae8184f6f..dbd125b5cca 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
@@ -211,7 +211,7 @@ int stm32_bringup(void)
}
#endif
-#ifdef CONFIG_ADC
+#if defined(CONFIG_ADC) && defined(CONFIG_STM32_ADC1)
/* Initialize ADC and register the ADC driver. */
ret = stm32_adc_setup();
@@ -369,5 +369,13 @@ int stm32_bringup(void)
}
#endif
+#ifdef CONFIG_ADC_HX711
+ ret = stm32_hx711_initialize();
+ if (ret != OK)
+ {
+ aerr("ERROR: Failed to initialize hx711: %d\n", ret);
+ }
+#endif
+
return ret;
}
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/stm32_hx711.c
b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_hx711.c
new file mode 100644
index 00000000000..72cd27966dc
--- /dev/null
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_hx711.c
@@ -0,0 +1,104 @@
+/****************************************************************************
+ * boards/arm/stm32/stm32f401rc-rs485/src/stm32_hx711.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership. The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/analog/hx711.h>
+#include <nuttx/compiler.h>
+#include <arch/board/board.h>
+#include <arch/stm32/chip.h>
+#include <debug.h>
+
+#include "stm32_gpio.h"
+#include "stm32f401rc-rs485.h"
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int stm32_hx711_clock_set(unsigned char minor, int value);
+static int stm32_hx711_data_read(unsigned char minor);
+static int stm32_hx711_data_irq(unsigned char minor,
+ xcpt_t handler, void *arg);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+struct hx711_lower_s g_lower =
+{
+ .data_read = stm32_hx711_data_read,
+ .clock_set = stm32_hx711_clock_set,
+ .data_irq = stm32_hx711_data_irq,
+ .cleanup = NULL
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static int stm32_hx711_clock_set(unsigned char minor, int value)
+{
+ UNUSED(minor);
+
+ stm32_gpiowrite(HX711_CLK_PIN, value);
+ return OK;
+}
+
+static int stm32_hx711_data_read(unsigned char minor)
+{
+ UNUSED(minor);
+
+ return stm32_gpioread(HX711_DATA_PIN);
+}
+
+static int stm32_hx711_data_irq(unsigned char minor,
+ xcpt_t handler, void *arg)
+{
+ UNUSED(minor);
+
+ return stm32_gpiosetevent(HX711_DATA_PIN, false, true, true, handler, arg);
+};
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int stm32_hx711_initialize(void)
+{
+ int ret;
+
+ stm32_configgpio(HX711_DATA_PIN);
+ stm32_configgpio(HX711_CLK_PIN);
+
+ ret = hx711_register(0, &g_lower);
+ if (ret != 0)
+ {
+ aerr("ERROR: Failed to register hx711 device: %d\n", ret);
+ return -1;
+ }
+
+ return OK;
+}
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
b/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
index a257063d5e9..46c2b900ec3 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
@@ -159,6 +159,15 @@
#define GPIO_INT1 (GPIO_INPUT | GPIO_PULLDOWN | GPIO_SPEED_2MHz | \
GPIO_PORTC | GPIO_PIN4)
+/* HX711 PINs */
+#ifdef CONFIG_ADC_HX711
+# define HX711_CLK_PIN (GPIO_OUTPUT|GPIO_PUSHPULL|GPIO_OUTPUT_SET|\
+ GPIO_SPEED_2MHz|GPIO_PULLUP|\
+ GPIO_PORTB|GPIO_PIN1)
+# define HX711_DATA_PIN (GPIO_INPUT|GPIO_SPEED_2MHz|GPIO_PULLUP|GPIO_EXTI|\
+ GPIO_PORTB|GPIO_PIN2)
+#endif /* CONFIG_ADC_HX711 */
+
/****************************************************************************
* Public Data
****************************************************************************/
@@ -305,4 +314,16 @@ int stm32_gpio_initialize(void);
int stm32_adc_setup(void);
#endif
+/****************************************************************************
+ * Name: stm32_hx711_initialize
+ *
+ * Description:
+ * Initialize hx711 chip
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_ADC_HX711
+int stm32_hx711_initialize(void);
+#endif
+
#endif /* __BOARDS_ARM_STM32_STM32F401RC_RS485_SRC_STM32F401RC_RS485_H */
