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drivers/sensors: Add support to MT6816

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This commit adds support to MagTek MT6816 sensor

Signed-off-by: Alan C. Assis <acassis@gmail.com>
This commit is contained in:
Alan Carvalho de Assis
2026-04-25 16:54:09 -03:00
committed by Alan C. Assis
parent 04d5cad64e
commit a1d6016962
5 changed files with 515 additions and 0 deletions
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drivers/sensors/CMakeLists.txt
+4
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@@ -107,6 +107,10 @@ if(CONFIG_SENSORS)
list(APPEND SRCS ak09912.c)
endif()
if(CONFIG_SENSORS_MT6816)
list(APPEND SRCS mt6816.c)
endif()
if(CONFIG_SENSORS_AS5048B)
list(APPEND SRCS as5048b.c)
endif()
drivers/sensors/Kconfig
+9
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@@ -161,6 +161,15 @@ config SENSORS_AK09912
---help---
Enable driver for AK09911/AK09912 Compass sensor.
config SENSORS_MT6816
bool "MagTek MT6816 Magnetic Angle Position support"
default n
select SPI
select SENSORS_QENCODER
---help---
Enable driver support for the MagTek MT6816 magnetic angle
position (magnetic rotary encoder).
config SENSORS_AS5048B
bool "AMS AS5048B Magnetic Rotary Encoder support"
default n
drivers/sensors/Make.defs
+4
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@@ -388,6 +388,10 @@ ifeq ($(CONFIG_SENSORS_MPL115A),y)
CSRCS += mpl115a.c
endif
ifeq ($(CONFIG_SENSORS_MT6816),y)
CSRCS += mt6816.c
endif
ifeq ($(CONFIG_SENSORS_LIS3MDL),y)
CSRCS += lis3mdl.c
endif
drivers/sensors/mt6816.c
+396
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@@ -0,0 +1,396 @@
/****************************************************************************
* drivers/sensors/mt6816.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 <assert.h>
#include <errno.h>
#include <nuttx/debug.h>
#include <stdlib.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/spi/spi.h>
#include <nuttx/sensors/mt6816.h>
#if defined(CONFIG_SENSORS_MT6816)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MT6816_REG_ANGLE_LSB 0x03
#define MT6816_REG_ANGLE_MSB 0x04
#define MT6816_CMD_READ 0x80
#define MT6816_NO_MAG_WARN 0x02
#define MT6816_PARITY_CHECK 0x01
/****************************************************************************
* Private Types
****************************************************************************/
struct mt6816_dev_s
{
struct qe_lowerhalf_s lower; /* MT6816 quadrature encoder lower half */
FAR struct spi_dev_s *spi; /* SPI interface */
/* Since multiple MT6816 can be connected to the same SPI bus we need
* to use multiple spi device ids which are employed by NuttX to select/
* deselect the desired MT6816 chip via their chip select inputs.
*/
int devid;
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static int mt6816_exchange(FAR struct mt6816_dev_s *priv,
uint8_t regaddr, FAR uint8_t *regval);
static uint16_t calc_even_parity(uint16_t value);
static int mt6816_readang(FAR struct mt6816_dev_s *priv,
FAR uint16_t *ang);
/* Character Driver Methods */
static int mt6816_setup(FAR struct qe_lowerhalf_s *lower);
static int mt6816_shutdown(FAR struct qe_lowerhalf_s *lower);
static int mt6816_position(FAR struct qe_lowerhalf_s *lower,
FAR int32_t *pos);
static int mt6816_reset(FAR struct qe_lowerhalf_s *lower);
static int mt6816_ioctl(FAR struct qe_lowerhalf_s *lower, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct qe_ops_s g_qeops =
{
mt6816_setup, /* setup */
mt6816_shutdown, /* shutdown */
mt6816_position, /* position */
NULL, /* setposmax */
mt6816_reset, /* reset */
NULL, /* setindex */
mt6816_ioctl /* ioctl */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: mt6816_configspi
*
* Description:
*
****************************************************************************/
static inline void mt6816_configspi(FAR struct spi_dev_s *spi)
{
/* Configure SPI for the MT6816 */
SPI_SETMODE(spi, MT6816_SPI_MODE);
SPI_SETBITS(spi, 8);
SPI_HWFEATURES(spi, 0);
SPI_SETFREQUENCY(spi, MT6816_SPI_MAXFREQUENCY);
}
/****************************************************************************
* Name: mt6816_exchange
*
* Description:
* Read from 8-bit registers
*
****************************************************************************/
static int mt6816_exchange(FAR struct mt6816_dev_s *priv,
uint8_t regaddr, FAR uint8_t *regval)
{
uint8_t dat;
/* If SPI bus is shared then lock and configure it */
SPI_LOCK(priv->spi, true);
mt6816_configspi(priv->spi);
/* Select the MT6816 */
SPI_SELECT(priv->spi, SPIDEV_MAG_ENCODER(priv->devid), true);
/* Send READ command. Received data is thrown away
* this data comes from the previous command (unknown)
*/
dat = MT6816_CMD_READ | regaddr;
/* Send register to read and get the next byte */
SPI_SEND(priv->spi, dat);
/* Send NOP command. Received data is the value of regaddr
* from the previous command
*/
dat = 0x00; /* NOP command */
*regval = SPI_SEND(priv->spi, dat);
/* Deselect the MT6816 */
SPI_SELECT(priv->spi, SPIDEV_MAG_ENCODER(priv->devid), false);
/* Unlock bus */
SPI_LOCK(priv->spi, false);
sninfo("addr: %02x value: %02x\n", regaddr, *regval);
return OK;
}
/****************************************************************************
* Name: calc_even_parity
*
* Description:
* get the even parity of input value
*
****************************************************************************/
static uint16_t calc_even_parity(uint16_t value)
{
uint16_t cnt = 0;
uint8_t i;
for (i = 0; i < 16; i++)
{
if (value & 0x1)
{
cnt++;
}
value >>= 1;
}
return cnt & 0x1;
}
/****************************************************************************
* Name: mt6816_readang
*
* Description:
* Read from the angle position registers
*
****************************************************************************/
static int mt6816_readang(FAR struct mt6816_dev_s *priv,
FAR uint16_t *ang)
{
uint8_t hi;
uint8_t lo;
uint16_t value;
bool no_mag;
bool parity;
int ret;
/* Read the high 8 bits of the 14-bit value */
ret = mt6816_exchange(priv, MT6816_REG_ANGLE_LSB, &hi);
if (ret < 0)
{
snerr("ERROR: mt6816_exchange failed: %d\n", ret);
return ret;
}
/* Read the low 6 bits of the 14-bit value */
ret = mt6816_exchange(priv, MT6816_REG_ANGLE_MSB, &lo);
if (ret < 0)
{
snerr("ERROR: mt6816_exchange failed: %d\n", ret);
return ret;
}
/* Read No Magnetic Error and Parity Check bits first */
no_mag = (lo & MT6816_NO_MAG_WARN) >> 1;
parity = (lo & MT6816_PARITY_CHECK);
value = ((uint16_t)hi << 8 | (uint16_t)lo);
/* Check if parity is right:
* - Clear the parity bit
* - Check if the calculated parity match with internal parity
*/
value &= ~MT6816_PARITY_CHECK;
if (calc_even_parity(value) == parity)
{
sninfo("Parity is correct!\n");
}
else
{
snerr("Parity error: expected %d got %d", !parity, parity);
}
/* Save only the angle value */
*ang = value >> 2;
sninfo("angle: %04d, NO_MAG=%d, PC=%d ret: %d\n",
*ang, no_mag, parity, ret);
return ret;
}
/****************************************************************************
* Name: mt6816_setup
*
* Description:
* This method is called when the driver is opened
*
****************************************************************************/
static int mt6816_setup(FAR struct qe_lowerhalf_s *lower)
{
return OK;
}
/****************************************************************************
* Name: mt6816_shutdown
*
* Description:
* This method is called when the driver is closed
*
****************************************************************************/
static int mt6816_shutdown(FAR struct qe_lowerhalf_s *lower)
{
return OK;
}
/****************************************************************************
* Name: mt6816_position
*
* Description:
* Return the current position measurement
*
****************************************************************************/
static int mt6816_position(FAR struct qe_lowerhalf_s *lower,
FAR int32_t *pos)
{
FAR struct mt6816_dev_s *priv = (FAR struct mt6816_dev_s *)lower;
uint16_t ang;
int ret;
ret = mt6816_readang(priv, &ang);
if (ret < 0)
{
snerr("ERROR: mt6816_readang failed: %d\n", ret);
return ret;
}
*pos = (int32_t)ang;
return ret;
}
/****************************************************************************
* Name: mt6816_reset
*
* Description:
* Reset the position measurement to zero
*
****************************************************************************/
static int mt6816_reset(FAR struct qe_lowerhalf_s *lower)
{
/* Seems like the MT6816 doesn't have a SPI writable register
* to define the zero position. However it has a register to
* flash the zero position using its memory programming (MTP)
* but it requires supply high voltage (7V) to HVPP pin.
*/
return OK;
}
/****************************************************************************
* Name: mt6816_ioctl
****************************************************************************/
static int mt6816_ioctl(FAR struct qe_lowerhalf_s *lower, int cmd,
unsigned long arg)
{
/* There is nothing we can('t) do! */
return OK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mt6816_initialize
*
* Description:
* Initialize the MT6816 device.
*
* Input Parameters:
* spi - An SPI driver instance.
*
* Returned Value:
* A new lower half encoder interface for the MT6816 on success;
* NULL on failure.
*
****************************************************************************/
FAR struct qe_lowerhalf_s *mt6816_initialize(FAR struct spi_dev_s *spi,
uint16_t devid)
{
FAR struct mt6816_dev_s *priv;
DEBUGASSERT(spi != NULL);
/* Initialize the device's structure */
priv = kmm_malloc(sizeof(*priv));
if (priv == NULL)
{
snerr("ERROR: Failed to allocate instance\n");
return NULL;
}
priv->lower.ops = &g_qeops;
priv->spi = spi;
priv->devid = devid;
return &priv->lower;
}
#endif /* CONFIG_SENSORS_MT6816 */
include/nuttx/sensors/mt6816.h
+102
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@@ -0,0 +1,102 @@
/****************************************************************************
* include/nuttx/sensors/mt6816.h
*
* 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.
*
****************************************************************************/
#ifndef __INCLUDE_NUTTX_SENSORS_MT6816_H
#define __INCLUDE_NUTTX_SENSORS_MT6816_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/spi/spi.h>
#include <nuttx/sensors/qencoder.h>
#if defined(CONFIG_SENSORS_MT6816)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************
* Prerequisites:
*
* CONFIG_SPI
* Enables support for SPI drivers
* CONFIG_SENSORS_MT6816
* Enables support for the MT6816 driver
*/
/* The device always operates in mode 3 */
#define MT6816_SPI_MODE SPIDEV_MODE3 /* Mode 3 */
/* SPI frequency */
#define MT6816_SPI_MAXFREQUENCY 1000000 /* 1MHz */
/* Resolution ***************************************************************/
#define MT6816_MAX 0x3fff /* Maximum value (14 bits) */
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
/****************************************************************************
* Name: mt6816_initialize
*
* Description:
* Initialize the MT6816 device.
*
* Input Parameters:
* spi - An SPI driver instance.
*
* Returned Value:
* A new lower half encoder interface for the MT6816 on success;
* NULL on failure.
*
****************************************************************************/
FAR struct qe_lowerhalf_s *mt6816_initialize(FAR struct spi_dev_s *spi,
uint16_t devid);
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* CONFIG_SENSORS_MT6816 */
#endif /* __INCLUDE_NUTTX_SENSORS_MT6816_H */