I2C and LM75 Temperature Sensor communication example
(C) COPYRIGHT 2015 WIZnet Co.,Ltd.
- file : I2C/I2C_Temperture_LM75A/readme.md
- author : IOP Team
- version : V1.0.0
- date : 1-May-2015
- brief : Description of the I2C and LM75 Temperature Sensor communication example.
THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME. AS A RESULT, WIZNET SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
Example Description
This example provides a description of how to use I2C to communicate with a LM75 I2C temperature sensor is mounted on the evaluation board and used to get instantaneous external temperature.
Directory contents
- I2C/I2C_Temperture_LM75A/main.c (Main program)
- I2C/I2C_Temperture_LM75A/W7500x_it.c (Interrupt Handlers)
- I2C/I2C_Temperture_LM75A/W7500x_it.h (Interrupt Handlers Header file)
- I2C/I2C_Temperture_LM75A/W7500x_conf.h (Library Configuration file)
- I2C/I2C_Temperture_LM75A/MDK//W7500x_I2C_Temperture_LM75A.uvproj (Project file)
- I2C/I2C_Temperture_LM75A/GCC/Makefile (GCC Make file)
Hardware and Software environment
--W7500-- --LM75--
| | | |
| SDA |------| SDA |
| SCL |------| SCL |
| | | |
| | | |
--------- ---------
LM75 Pin Configuration
-----
SDA |1 8| VCC
SCL |2 7| A0
OS |3 6| A1
GND |4 5| A2
-----
LM75 Pin Description
| PIN | SYMBOL | DESCRIPTION |
|---|---|---|
| 1 | SDA | Digital I/O. I2C serial bi-directional data line. Open Drain |
| 2 | SCL | Digital input. I2C serial clock input. |
| 3 | OS | Overtemp Shutdown output. Open Drain. |
| 4 | GND | Ground. To be connected to the system ground. |
| 5 | A2 | Digital input. User-defined address bit2. |
| 6 | A1 | Digital input. User-defined address bit1. |
| 7 | A0 | Digital input. User-defined address bit0. |
| 8 | VCC | Power supply. |
LM75 register
| REG NAME | Addr | R/W | RST Value | DESCRIPTION |
|---|---|---|---|---|
| Temp | 0x00 | R/W | 0x0000 | Configuration Register. Contains a single 8-bit data byte. To set the device operating condition Default = 0. |
| Conf | 0x01 | R | N/A | Temperature Register. Contains two 8-bit data bytes. To store the measured Temp data. |
| Thyrs | 0x02 | R/W | 0x5000 | Over-temp Shutdown threshold Register. Contains two 8-bit data bytes. To store the over-temp shut-down Tos limit. Default = 80c |
| Tos | 0x03 | R/W | 0x4B00 | Hysteresis Register. Contains two 8-bit data bytes. To store the hysteresis Thyst limit. Default = 75C. |
LM75 Device Address
--- --- --- --- --- --- ---
| 1 | 0 | 0 | 1 |A2 | A1| A0|
--- --- --- --- --- --- ---
LSB
LM75 Temp register table
| Temp MS byte | Temp LS byte | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| MSB | LSB | MSB | LSB | ||||||||||||
| B7 | B6 | B5 | B4 | B3 | B2 | B1 | B0 | B7 | B6 | B5 | B4 | B3 | B2 | B1 | B0 |
| Temp data(11bits) | Not Used | ||||||||||||||
| MSB | LSB | MSB | LSB | ||||||||||||
| D10 | D9 | D8 | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 | X | X | X | X | X |
How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain.
- Rebuild all files and load your image into target memory.
- Run the example.
- WIZwiki W7500 where the Flash memory density ranges 128Kbytes.
- If you have any questions, please use the forum site.
Flow Chart
- Master Init
- Slave address send from W7500 to LM75
- START enable
- Confirm the Ack Receive
- Send the data from W7500 to LM75
- Restart enable
- Confirm the Ack Receive
- Receive the data
- Transmit the Ack transmission
- STOP enable
© COPYRIGHT 2015 WIZnet Co.,Ltd.