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drivers/analog/hx711.c: Add driver for hx711 adc
Signed-off-by: Michał Łyszczek <michal.lyszczek@bofc.pl>
This commit is contained in:
Michał Łyszczek
committed by
Alan Carvalho de Assis
Alan Carvalho de Assis
parent
b634798bd6
commit
84a2cab886
@@ -0,0 +1,212 @@
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/****************************************************************************
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* include/nuttx/analog/hx711.h
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/compiler.h>
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#include <nuttx/irq.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define HX711_MAX_AVG_SAMPLES 225
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/* ioctl requests ***********************************************************/
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/* Set how many samples to read from hx711 to get a single averaged value.
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* Minimum value is 1. To prevent possible integer overflow, maximum value
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* is HX711_MAX_AVG_SAMPLES.
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*/
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#define HX711_SET_AVERAGE 0
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/* Set channel to use for next read() operation. Channels 'a' and 'b'
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* are available. Specify channel as 'a' character (0x61 hex)
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*/
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#define HX711_SET_CHANNEL 1
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/* Set gain to use for next read() operation. Channel 'b' only supports
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* gain of 32, and channel 'a' supports gain 128 and 64
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*/
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#define HX711_SET_GAIN 2
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/* Set what value coresponds to 1 unit. Takes integer.
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* If set to 0 (default) driver will return raw readings from
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* hx711 instead of calculated units.
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*/
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#define HX711_SET_VAL_PER_UNIT 3
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/* Depending on tensometer position, value will go higher or lower
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* (into negative values) when mass increases. If your sign does
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* not match, it can be changed by calling this.
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* 1 - no sign change (default)
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* -1 - sign will be changed
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*/
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#define HX711_SET_SIGN 4
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/* ioctl get functions */
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/* Get current average, pass pointer to unsigned int type */
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#define HX711_GET_AVERAGE 100
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/* Get current channel, pass pointer to single char */
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#define HX711_GET_CHANNEL 101
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/* Get current gain, pass pointer to single unsignedchar */
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#define HX711_GET_GAIN 102
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/* Get current value per unit */
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#define HX711_GET_VAL_PER_UNIT 103
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/* Tare the scale. Accepts int value with desired precision.
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* If HX711_VAL_PER_UNIT was set earlier, you should pass value
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* in units, otherwise you need to pass raw value as read from hx711.
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* Takes pointer to a float value.
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*/
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#define HX711_TARE 200
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/****************************************************************************
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* Public Types
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****************************************************************************/
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/* hx711 exposes 2 pins for communication. One is for data reading, and
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* second one is clock signal. This is similar to i2c but hx711 uses custom
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* protocol that is not compatible with i2c in any way.
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*
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* Platform code should provide these functions to manipulate these GPIOs
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*/
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struct hx711_lower_s
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{
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/**************************************************************************
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* Name: clock_set
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*
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* Description:
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* Sets underlying GPIO pin according to val.
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*
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* Input Parameters:
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* val - set GPIO pin high (1) or low (0)
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* minor - hx711 device being manipulated
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*
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* Returned Value:
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* OK on success, or negated errno on failure
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*
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**************************************************************************/
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CODE int (*clock_set)(unsigned char minor, int val);
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/**************************************************************************
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* Name: data_read
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*
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* Description:
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* Reads current value of data GPIO pin.
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*
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* Input Parameters:
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* minor - hx711 device being manipulated
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*
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* Returned Value:
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* For success, return 0 when GPIO is low, 1 when GPIO is high
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* or negated errno on failure.
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*
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**************************************************************************/
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CODE int (*data_read)(unsigned char minor);
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/**************************************************************************
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* Name: cleanup
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*
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* Description:
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* This function is called when last instance of minor is closed and
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* unlinked from fs so that hx711 minor instance is no longer available.
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* Platform should free all resources it allocated to register the
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* device.
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*
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* This function does not have to be set, if there is nothing to clean.
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*
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* Input Parameters:
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* minor - hx711 instance being destroyed
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*
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**************************************************************************/
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CODE void (*cleanup)(unsigned char minor);
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/**************************************************************************
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* Name: data_irq
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*
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* Description:
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* Setup (or tear down when handler is NULL) interrupt when data line
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* goes from HIGH to LOW state (falling edge).
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*
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* hx711 is slow, on internal oscillator and RATE=0 it takes 100ms to
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* sample a single reading. To avoid hogging CPU polling for data to
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* go down, driver will install interrupt handler before reading.
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* Once interrupt is received, driver will disable the handler.
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*
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* Input Parameters:
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* minor - hx711 device being manipulated
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* handler - function interrupt should call
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* arg - private data for handler, should be passed to handler
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*
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* Returned Value:
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* On successfull interrupt initialization 0 should be returned,
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* when there was failure initializing interrupt -1 shall be returned.
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*
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**************************************************************************/
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CODE int (*data_irq)(unsigned char minor, xcpt_t handler, void *arg);
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};
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/****************************************************************************
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* Public Functions Prototypes
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****************************************************************************/
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/****************************************************************************
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* Name: hx711_register
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*
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* Description:
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* Register new hx711 device in /dev/hx711_%d. Multiple hx711 can be
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* supported by providing different minor number. When driver calls
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* platform specific function, minor number is passed back, so platform
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* can know which hx711 is manipulated.
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*
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* Input Parameters:
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* minor - unique number identifying hx711 chip.
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* lower - provided by platform code to manipulate hx711 with platform
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* dependant functions>
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*
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* Returned Value:
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* OK on success, or negated errno on failure
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*
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****************************************************************************/
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int hx711_register(unsigned char minor, FAR struct hx711_lower_s *lower);
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