diff --git a/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst b/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
index 785e6cbf23..e255110fbc 100644
--- a/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
+++ b/Documentation/platforms/arm/stm32f4/boards/stm32f401rc-rs485/index.rst
@@ -442,3 +442,26 @@ NSH commands::
        1: channel: 4 value: 2682
 
 Currently there is a bug that causes the application to always read the same value for channel 0 and 4. If you want to read the value from channel 2, you will need to enable the config "ADC1 Scan Mode".
+
+dac
+---
+
+Configures the NuttShell (nsh) over USB Serial (check usbserial configuration) and enables PWM 3 on channel 1.
+Use pwm command on NSH to change dutty cycle, frequency and duration, use dac_out_2 to measure the output voltage. 
+NSH commands::
+
+       nsh> pwm -h
+       Usage: pwm [OPTIONS]
+
+       Arguments are "sticky".  For example, once the PWM frequency is
+       specified, that frequency will be re-used until it is changed.
+
+       "sticky" OPTIONS include:
+         [-p devpath] selects the PWM device.  Default: /dev/pwm0 Current: NONE
+         [-f frequency] selects the pulse frequency.  Default: 100 Hz Current: 100 Hz
+         [-d duty] selects the pulse duty as a percentage.  Default: 50 % Current: 50 %
+         [-t duration] is the duration of the pulse train in seconds.  Default: 5 Current: 5
+         [-h] shows this message and exits
+       nsh> pwm -d 50 -t 3
+       pwm_main: starting output with frequency: 50 duty: 00007fff
+       pwm_main: stopping output
diff --git a/boards/arm/stm32/stm32f401rc-rs485/configs/dac/defconfig b/boards/arm/stm32/stm32f401rc-rs485/configs/dac/defconfig
new file mode 100644
index 0000000000..bff4a70526
--- /dev/null
+++ b/boards/arm/stm32/stm32f401rc-rs485/configs/dac/defconfig
@@ -0,0 +1,67 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_ARCH_FPU is not set
+# CONFIG_NSH_ARGCAT is not set
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+# CONFIG_NSH_DISABLE_IFCONFIG is not set
+# CONFIG_NSH_DISABLE_PS is not set
+CONFIG_ARCH="arm"
+CONFIG_ARCH_BOARD="stm32f401rc-rs485"
+CONFIG_ARCH_BOARD_STM32F401RC_RS485=y
+CONFIG_ARCH_BUTTONS=y
+CONFIG_ARCH_CHIP="stm32"
+CONFIG_ARCH_CHIP_STM32=y
+CONFIG_ARCH_CHIP_STM32F401RC=y
+CONFIG_ARCH_INTERRUPTSTACK=2048
+CONFIG_ARCH_IRQBUTTONS=y
+CONFIG_ARCH_STACKDUMP=y
+CONFIG_BOARDCTL_USBDEVCTRL=y
+CONFIG_BOARD_LOOPSPERMSEC=8499
+CONFIG_BUILTIN=y
+CONFIG_CDCACM=y
+CONFIG_CDCACM_CONSOLE=y
+CONFIG_EXAMPLES_BUTTONS=y
+CONFIG_EXAMPLES_BUTTONS_NAME0="SW3"
+CONFIG_EXAMPLES_BUTTONS_NAME1="SW4"
+CONFIG_EXAMPLES_BUTTONS_NAME2="SW5"
+CONFIG_EXAMPLES_BUTTONS_NAMES=y
+CONFIG_EXAMPLES_BUTTONS_QTD=3
+CONFIG_EXAMPLES_PWM=y
+CONFIG_HAVE_CXX=y
+CONFIG_HAVE_CXXINITIALIZE=y
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_INPUT=y
+CONFIG_INPUT_BUTTONS=y
+CONFIG_INPUT_BUTTONS_LOWER=y
+CONFIG_INTELHEX_BINARY=y
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILEIOSIZE=512
+CONFIG_NSH_LINELEN=64
+CONFIG_NSH_READLINE=y
+CONFIG_PREALLOC_TIMERS=4
+CONFIG_PWM=y
+CONFIG_RAM_SIZE=98304
+CONFIG_RAM_START=0x20000000
+CONFIG_RAW_BINARY=y
+CONFIG_RR_INTERVAL=200
+CONFIG_SCHED_WAITPID=y
+CONFIG_SPI=y
+CONFIG_START_DAY=5
+CONFIG_START_MONTH=5
+CONFIG_START_YEAR=2014
+CONFIG_STM32_JTAG_SW_ENABLE=y
+CONFIG_STM32_OTGFS=y
+CONFIG_STM32_PWR=y
+CONFIG_STM32_TIM3=y
+CONFIG_STM32_TIM3_CH1OUT=y
+CONFIG_STM32_TIM3_PWM=y
+CONFIG_STM32_USART6=y
+CONFIG_SYSTEM_NSH=y
+CONFIG_TASK_NAME_SIZE=0
+CONFIG_USBDEV=y
diff --git a/boards/arm/stm32/stm32f401rc-rs485/include/board.h b/boards/arm/stm32/stm32f401rc-rs485/include/board.h
index 016ce5a840..17e9112e5a 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/include/board.h
+++ b/boards/arm/stm32/stm32f401rc-rs485/include/board.h
@@ -282,6 +282,14 @@ extern "C"
 #define GPIO_USART6_RX   GPIO_USART6_RX_1    /* PC7 */
 #define GPIO_USART6_TX   GPIO_USART6_TX_1    /* PC6 */
 
+/* PWM
+ *
+ * The STM32F401RC-RS485 has no real on-board PWM devices, but the board
+ * can be configured to output a pulse train using TIM3 CH1 on PA6.
+ */
+
+#define GPIO_TIM3_CH1OUT  GPIO_TIM3_CH1OUT_1
+
 /* I2C
  *
  * The optional _GPIO configurations allow the I2C driver to manually
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt b/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
index 0c55188cb6..3baadaff60 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/CMakeLists.txt
@@ -52,6 +52,10 @@ if(CONFIG_STM32_CONFIG_I2C_EE_24XXEEPROM)
   list(APPEND SRCS stm32_at24.c)
 endif()
 
+if(CONFIG_STM32_PWM)
+  list(APPEND SRCS stm32_pwm.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 02b7c3f4f0..5eff56f7be 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/Make.defs
@@ -55,6 +55,10 @@ ifeq ($(CONFIG_I2C_EE_24XX),y)
 CSRCS += stm32_at24.c
 endif
 
+ifeq ($(CONFIG_STM32_PWM),y)
+CSRCS += stm32_pwm.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 98c1be0e9e..e0a486a252 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_bringup.c
@@ -179,6 +179,16 @@ int stm32_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_PWM
+  /* Initialize PWM and register the PWM device */
+
+  ret = stm32_pwm_setup();
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "ERROR: stm32_pwm_setup() failed: %d\n", ret);
+    }
+#endif
+
 #ifdef HAVE_SDIO
   /* Initialize the SDIO block driver */
 
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/stm32_pwm.c b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_pwm.c
new file mode 100644
index 0000000000..80eacc9964
--- /dev/null
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32_pwm.c
@@ -0,0 +1,119 @@
+/****************************************************************************
+ * boards/arm/stm32/stm32f401rc-rs485/src/stm32_pwm.c
+ *
+ * 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 <errno.h>
+#include <debug.h>
+
+#include <nuttx/timers/pwm.h>
+#include <arch/board/board.h>
+
+#include "chip.h"
+#include "arm_internal.h"
+#include "stm32_pwm.h"
+#include "stm32f401rc-rs485.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* Configuration ************************************************************/
+
+/* PWM
+ *
+ * The STM32F401RC-RS485 has no real on-board PWM devices, but the board can
+ * be configured to output a pulse train using TIM3 CH1.
+ *
+ */
+
+#define HAVE_PWM 1
+
+#ifndef CONFIG_PWM
+#  undef HAVE_PWM
+#endif
+
+#ifndef CONFIG_STM32_TIM3
+#  undef HAVE_PWM
+#endif
+
+#ifndef CONFIG_STM32_TIM3_PWM
+#  undef HAVE_PWM
+#endif
+
+#if !defined(CONFIG_STM32_TIM3_CHANNEL) || CONFIG_STM32_TIM3_CHANNEL != STM32F401RCRS485_PWMCHANNEL
+#  undef HAVE_PWM
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: stm32_pwm_setup
+ *
+ * Description:
+ *   Initialize PWM and register the PWM device.
+ *
+ ****************************************************************************/
+
+int stm32_pwm_setup(void)
+{
+#ifdef HAVE_PWM
+  static bool initialized = false;
+  struct pwm_lowerhalf_s *pwm;
+  int ret;
+
+  /* Have we already initialized? */
+
+  if (!initialized)
+    {
+      /* Call stm32_pwminitialize() to get an instance of the PWM interface */
+
+      pwm = stm32_pwminitialize(STM32F401RCRS485_PWMTIMER);
+      if (!pwm)
+        {
+          aerr("ERROR: Failed to get the STM32 PWM lower half\n");
+          return -ENODEV;
+        }
+
+      /* Register the PWM driver at "/dev/pwm0" */
+
+      ret = pwm_register("/dev/pwm0", pwm);
+      if (ret < 0)
+        {
+          aerr("ERROR: pwm_register failed: %d\n", ret);
+          return ret;
+        }
+
+      /* Now we are initialized */
+
+      initialized = true;
+    }
+
+  return OK;
+#else
+  return -ENODEV;
+#endif
+}
diff --git a/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h b/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
index 3cfd28a35c..691fb56cec 100644
--- a/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
+++ b/boards/arm/stm32/stm32f401rc-rs485/src/stm32f401rc-rs485.h
@@ -113,6 +113,15 @@
      GPIO_OUTPUT_SET | GPIO_PORTB | GPIO_PIN5)
 #endif
 
+/* PWM
+ *
+ * The STM32F401RC-RS485 has no real on-board PWM devices, but the board can
+ * be configured to output a pulse train using TIM3 CH1 on PA6.
+ */
+
+#define STM32F401RCRS485_PWMTIMER   3
+#define STM32F401RCRS485_PWMCHANNEL 1
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/
@@ -185,6 +194,21 @@ void stm32_usbinitialize(void);
 int stm32_adc_setup(void);
 #endif
 
+/****************************************************************************
+ * Name: stm32_pwm_setup
+ *
+ * Description:
+ *   Initialize PWM and register the PWM device.
+ *
+ * Return Value:
+ *   OK on success; a negated errno value on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_PWM
+int stm32_pwm_setup(void);
+#endif
+
 /****************************************************************************
  * Name: stm32_sdio_initialize
  *