Raspberries/mraa
Private
Public Access
2
0
Fork 0
Code Activity

uart_ow: Initial support for Dallas 1-wire over UART support for MRAA

Browse Source 
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>
This commit is contained in:
Jon Trulson
2015-12-15 17:11:14 -07:00
committed by Brendan Le Foll
parent 69d9c26e6e
commit a379eb7bf6
12 changed files with 1143 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
examples/CMakeLists.txt
View File

@@ -9,6 +9,7 @@ add_executable (spi_mcp4261 spi_mcp4261.c)
add_executable (mmap-io2 mmap-io2.c)
add_executable (blink_onboard blink_onboard.c)
add_executable (uart uart.c)
add_executable (uart_ow uart_ow.c)
add_executable (mraa-gpio mraa-gpio.c)
add_executable (mraa-i2c mraa-i2c.c)
add_executable (spi_max7219 spi_max7219.c)
@@ -30,6 +31,7 @@ target_link_libraries (spi_mcp4261 mraa)
target_link_libraries (mmap-io2 mraa)
target_link_libraries (blink_onboard mraa)
target_link_libraries (uart mraa)
target_link_libraries (uart_ow mraa)
target_link_libraries (mraa-gpio mraa)
target_link_libraries (mraa-i2c mraa)
target_link_libraries (spi_max7219 mraa)

2
examples/c++/CMakeLists.txt
View File

@@ -8,6 +8,7 @@ add_executable (Spi-pot Spi-pot.cpp)
add_executable (Uart Uart-example.cpp)
add_executable (Isr-pin6 Isr-pin6.cpp)
add_executable (Iio-dummy Iio-dummy.cpp)
add_executable (UartOW UartOW.cpp)
include_directories(${PROJECT_SOURCE_DIR}/api)
@@ -19,3 +20,4 @@ target_link_libraries (Spi-pot mraa stdc++)
target_link_libraries (Uart mraa stdc++)
target_link_libraries (Isr-pin6 mraa stdc++)
target_link_libraries (Iio-dummy mraa stdc++)
target_link_libraries (UartOW mraa stdc++)

82
examples/c++/UartOW.cpp Normal file
View File

@@ -0,0 +1,82 @@
/*
* Author: Jon Trulson <jtrulson@ics.com>
* Copyright (c) 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "stdio.h"
#include "iostream"
//! [Interesting]
#include "uart_ow.hpp"
using namespace std;
int
main(int argc, char** argv)
{
mraa::UartOW* uart = new mraa::UartOW(0);
// Reset the ow bus and see if anything is present
mraa::Result rv;
if ((rv = uart->reset()) == mraa::SUCCESS) {
cout << "Reset succeeded, device(s) detected!" << endl;
} else {
cout << "Reset failed, returned " << int(rv) << ". No devices on bus?" << endl;
return 1;
}
cout << "Looking for devices..." << endl;
;
uint8_t count = 0;
// start the search from scratch
string id = uart->search(true);
if (id.empty()) {
cout << "No devices detected." << endl;
return 1;
}
while (!id.empty()) {
// hack so we don't need to cast each element of the romcode
// for printf purposes
uint8_t* ptr = (uint8_t*) id.c_str();
// The first byte (0) is the device type (family) code.
// The last byte (7) is the rom code CRC value. The
// intervening bytes are the unique 48 bit device ID.
printf("Device %02d Type 0x%02x ID %02x%02x%02x%02x%02x%02x CRC 0x%02x\n", count, ptr[0],
ptr[6], ptr[5], ptr[4], ptr[3], ptr[2], ptr[1], ptr[7]);
count++;
// continue the search with start argument set to false
id = uart->search(false);
}
cout << "Exiting..." << endl;
delete uart;
return 0;
}
//! [Interesting]

93
examples/uart_ow.c Normal file
View File

@@ -0,0 +1,93 @@
/*
* Author: Jon Trulson <jtrulson@ics.com>
* Copyright (c) 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "stdio.h"
//! [Interesting]
#include "mraa.h"
int
main(int argc, char** argv)
{
mraa_uart_ow_context uart;
uart = mraa_uart_ow_init(0);
if (!uart) {
printf("mraa_uart_ow_init() failed\n");
return 1;
}
// Reset the ow bus and see if anything is present
mraa_result_t rv;
if ((rv = mraa_uart_ow_reset(uart)) == MRAA_SUCCESS) {
printf("Reset succeeded, device(s) detected!\n");
} else {
printf("Reset failed, returned %d. No devices on bus?\n", rv);
return 1;
}
printf("Looking for devices...\n");
uint8_t id[MRAA_UART_OW_ROMCODE_SIZE];
/* we are essentially doing a binary tree search through the 64
* bit address space. id is modified during this search, and will
* be set to the valid rom code for each device found.
*/
uint8_t count = 0;
// start the search from scratch
uint8_t result = mraa_uart_ow_rom_search(uart, 1, id);
if (result == MRAA_ERROR_UART_OW_NO_DEVICES) {
printf("No devices detected.\n");
return 1;
}
if (result == MRAA_ERROR_UART_OW_DATA_ERROR) {
printf("Bus/Data error.\n");
return 1;
}
while (result == MRAA_SUCCESS) {
/* The first byte (id[0]]) is the device type (family) code.
* The last byte (id[7]) is the rom code CRC value. The
* intervening bytes (id[1]-id[6]) are the unique 48 bit
* device ID.
*/
printf("Device %02d Type 0x%02x ID %02x%02x%02x%02x%02x%02x CRC 0x%02x\n", count, id[0],
id[6], id[5], id[4], id[3], id[2], id[1], id[7]);
count++;
// continue the search with start argument set to 0
result = mraa_uart_ow_rom_search(uart, 0, id);
}
printf("Exiting...\n");
mraa_uart_ow_stop(uart);
return 0;
}
//! [Interesting]