a379eb7bf6
This commit introduces support for Dallas Semiconductor (DS) 1-wire compliant device support using an available UART device. The principle of operation is described in the following Application note by Maxim Electronics: https://www.maximintegrated.com/en/app-notes/index.mvp/id/214 with help (1-wire search) from: https://www.maximintegrated.com/en/app-notes/index.mvp/id/187 It has been tested on Galileo 2 and Edison, with 2 DS 1-wire devices, the DS18B20 and DS2413 connected to the bus. A UPM driver for the DS2413 is already complete and a PR will be submitted after this one. It is important that you use a UART with CMOS/TTL level voltages (3.3v/5v) RX and TX lines. DO NOT use standard RS232 level voltages or you are going to have a bad day. In order for this to work, a simple interface circuit, using a single diode must be constructed: (forgive my "Asciihematic" :) -| U| A| TX---|<--+ R| | T| RX-------o--------o 1-wire data bus -| The diode on TX is a 1N4148 (cheap and common), with the cathode connected to TX, and the anode connected to RX and the 1-wire data line. The 1-wire data line requires a pull-up resistor, as the DS 1-wire spec requires. 4.7-5K is typical for DS 1-wire buses. NOTE: DHT-type (temp/humidity sensor) 1-wire devices ARE NOT DS 1-wire compliant, and will not work with this code/circuit unfortunately. Also note, this will use up one of your UARTs, which cannot be used for any other purpose (ie: to access true UART-type serial devices). You can however, connect as many DS 1-wire devices as feasible to this UART, as it will function as a DS 1-wire bus master. Signed-off-by: Jon Trulson <jtrulson@ics.com> Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>
41 lines
1.4 KiB
C
41 lines
1.4 KiB
C
/*
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* Author: Brendan Le Foll <brendan.le.foll@intel.com>
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#pragma once
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "mraa/pwm.h"
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#include "mraa/aio.h"
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#include "mraa/gpio.h"
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#include "mraa/spi.h"
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#include "mraa/i2c.h"
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#include "mraa/uart.h"
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#include "mraa/uart_ow.h"
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#ifdef __cplusplus
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}
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#endif
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