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>
83 lines
2.6 KiB
C++
83 lines
2.6 KiB
C++
/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in 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,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "stdio.h"
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#include "iostream"
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//! [Interesting]
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#include "uart_ow.hpp"
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using namespace std;
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int
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main(int argc, char** argv)
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{
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mraa::UartOW* uart = new mraa::UartOW(0);
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// Reset the ow bus and see if anything is present
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mraa::Result rv;
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if ((rv = uart->reset()) == mraa::SUCCESS) {
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cout << "Reset succeeded, device(s) detected!" << endl;
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} else {
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cout << "Reset failed, returned " << int(rv) << ". No devices on bus?" << endl;
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return 1;
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}
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cout << "Looking for devices..." << endl;
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;
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uint8_t count = 0;
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// start the search from scratch
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string id = uart->search(true);
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if (id.empty()) {
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cout << "No devices detected." << endl;
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return 1;
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}
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while (!id.empty()) {
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// hack so we don't need to cast each element of the romcode
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// for printf purposes
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uint8_t* ptr = (uint8_t*) id.c_str();
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// The first byte (0) is the device type (family) code.
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// The last byte (7) is the rom code CRC value. The
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// intervening bytes are the unique 48 bit device ID.
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printf("Device %02d Type 0x%02x ID %02x%02x%02x%02x%02x%02x CRC 0x%02x\n", count, ptr[0],
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ptr[6], ptr[5], ptr[4], ptr[3], ptr[2], ptr[1], ptr[7]);
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count++;
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// continue the search with start argument set to false
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id = uart->search(false);
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}
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cout << "Exiting..." << endl;
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delete uart;
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return 0;
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}
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//! [Interesting]
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