DA14585/DA14586 OneWire example using DS18B20 temperature sensors¶

Example description¶

This SDK6 DA14585 example provides a implementation of a 1-Wire driver with three DS18B20 sensors (editing the MAX_NO_SENSORS value in the one_wire.h file will allow more sensors to be connected). The 1-Wire commands and sensordata are added in BLE characteristics to be controlled or read from a smartphone application (i.e. Lightblue for iOS or BLE Scanner for Android). More information on the DS18B20 can be found in the datasheet.

HW and SW configuration¶

Hardware configuration
- This example runs on The DA14585 Bluetooth Smart SoC devices.
- A breadboard is used for connecting the buscomponents to the develepment kit as shown in the lay-out schematic underneath. The jumper settings are displayed in pink.
- The Basic or pro Development kit is needed for this example.
- Connect the USB Development kit to the host computer.
- Button is configured to P1_1 corresponding to SW3 on the Pro Development kit.
- For the Basic development kit, an active-low switch should be connected to P1_1 as displayed in the schematic underneath
- The Rx pin of the bus is connected to P1_3 on both the Pro and Basic dev kit.
- The Tx pin of the bus is connected to P0_6 on both the Pro and Basic dev kit.
- A pull-up resistor of 4k7 Ohms should be connected to the bus. Connect the pull-up resistor to VBAT_580 on the dev kit.
- For powering the sensors Connect the sensor Vcc to VBAT_580 on the dev kit. The sensor gnd can be connected to gnd on the dev kit.
- A diode (i.e. 1N4148) should be connected to prevent the Tx pin from trying to drive the bus high whenever a slave pulls it low. The schematic underneath displays the connection from the 1-Wire bus to the dev kit.
Breadboard lay-out

Software configuration
- This example requires:
- Smartsnippets Studio 1.6.3.
- SDK6.0.10
- SEGGER’s J-Link tools should be downloaded and installed.

How to run the example¶

For initial setup of the example please refer to this section of the dialog support portal. The example is running from SRAM. For programming to Flash, see chapter 11 in the SmartSnippets Toolbox User Manual.

Initial Setup¶

Start Keil
Compile and launch the example
Open the serial terminal of your choice (i.e. Tera Term) with the following parameters.
- baudrate: 115200
- data: 8 bits
- stop: 1 bit
- parity: None
- flow control: none
Pressing the button (P1_1) will initiate the following sequence:
- SearchROMalgorithm to detect all slave (DS18B20) addresses on the bus
- Issue a Convert Temperature command to all the slaves (DS18B20).
- Read scratchpad of all the slaves (DS18B20).
- Send data to serial terminal via UART. An example of the data is displayed underneath.
  
  Data displayed using three sensors
In order to issue commands over BLE and receive sensordata on the smartphone the followings steps are required.
- Use a BLE application like LightBlue (iOS) to connect to the dev kit. The device name will be “OneWire-Example” with 0x036670CAEA80 as it’s BD address.
- In order to receive any data enable “Listen for notifications” in the “OneWire Sensor Data” characteristic as shown in the screenshot below.
- In the “OneWire Control Point” writing the following values will:
  - 0xF0 => Start the SearchROMalgorithm. When complete it will send the sensoraddress over BLE. It will also send send the addresses to serial terminal via UART.
  - 0x44 => Issue a convert temperature command.
  - 0xBE => Read scratchpad contents (72 bits) and send the last 56 bits of the scratchpad (exluding temperatures) over BLE. It will also send send the scratchpad data to serial terminal via UART.
  - 0x01 => Send the raw temperature data (16 bits) over BLE. It will also send the temperatures to serial terminal in degrees celcius.
  Enabling listen for notifications

About this example¶

Starting point for this example is the BLE peripheral project from SDK6. This project provides the right framework for adding the OneWire BLE characteristics. In the this project the user_one_wire and user_ds18b20 drivers were added.
The user_one_wire driver contains:
- All the functionality to transmit high level and low level bits using the SPI controller: OneWire_write_1(), OneWire_write_0(); The SPI controller is necessary to provide accurate timings. Below, two screenshots of a logic analyzer will display 3 bits of a transmission sequence and the corresponding timings achieved with the SPI controller of a Write 0 and Write 1 operation respectively.
- Function to transmit whole bytes: OneWire_write_byte(uint8_t byte);
- Master readslot function requiring a callback to determine specific functionality (i.e. id_systick_ISR for reading id bit in the search algorithm): OneWire_readSlot(systick_callback_function_t systick_callback);
- OneWire initialisation which sets up the SPI controller with the correct parameters: OneWire_init();
- OneWire reset pulse: OneWire_reset();
- Wait for presence pulse: OneWire_presence();
- Search ROM algorithm storing all addresses on the bus in struct array of type OneWire_sensor: OneWire_SearchROM();
- Configurable limit to the number of sensors: #define MAX_NO_SENSORS 10
Write 0 timings

Write 1 timings
The user_ds18b20 driver contains:
- Function to get only the DS18B20 address(es) using the OneWire_SearchROM() function. It will store the addresses (least significant 32 bits and most significant 32 bits seperately) in the correct members and instances of the struct array of type temperature_sensor: get_address(void);
- Function command to let all the DS18B20 convert the temperature and write it in the scratchpad. With the standard 12-bit resolution, it takes approximately 750ms: OneWire_ConvertT(void);
- Function to read the scratchpad contents. It will store the temperatures, and the rest of the scratchpad contents (24 least significant bits and 32 most significant bits) seperately in the correct members and instances of the struct array of type temperature_sensor: OneWire_readScratchpad(void);
- Function command to target a single sensor using the sensor index: OneWire_matchRom(int sensor_number);
- Functions to print data to the uart serial terminal: print_scratchpad(void), print_address(void), print_temperature(void);
For adding the BLE characteristics the following files were modified:
- For user_custs1_def (header and source file);
- user_custs1_impl (header and source file);
- user_peripheral.c
- For more info on adding a custom BLE profile, refer to this tutorial.

Known Limitations¶

There are No known limitations for this example. But you can check and refer to the following application note for known hardware limitations.
Dialog Software Forum link.
you can Refer also for the Troubleshooting section in the DA1585x Getting Started with the Development Kit UM-B-049.

License¶

This software (“Software”) is owned by Dialog Semiconductor. By using this Software you agree that Dialog Semiconductor retains all intellectual property and proprietary rights in and to this Software and any use, reproduction, disclosure or distribution of the Software without express written permission or a license agreement from Dialog Semiconductor is strictly prohibited. This Software is solely for use on or in conjunction with Dialog Semiconductor products.

EXCEPT AS OTHERWISE PROVIDED IN A LICENSE AGREEMENT BETWEEN THE PARTIES OR AS REQUIRED BY LAW, 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 NON-INFRINGEMENT. EXCEPT AS OTHERWISE PROVIDED IN A LICENSE AGREEMENT BETWEEN THE PARTIES OR BY LAW, IN NO EVENT SHALL DIALOG SEMICONDUCTOR BE LIABLE FOR ANY DIRECT, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THE SOFTWARE.