{"id":4359,"date":"2020-12-17T07:07:09","date_gmt":"2020-12-17T07:07:09","guid":{"rendered":"http:\/\/fastbitlab.com\/?p=4359"},"modified":"2023-09-07T14:28:39","modified_gmt":"2023-09-07T08:58:39","slug":"stm32-i2c-lecture-33-exercise-reading-data-from-the-i2c-slave","status":"publish","type":"post","link":"https:\/\/fastbitlab.com\/blog\/stm32-i2c-lecture-33-exercise-reading-data-from-the-i2c-slave\/","title":{"rendered":"STM32 I2C Lecture 33 – Exercise: Reading data from the I2C slave"},"content":{"rendered":"
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Exercise: Reading data from the I2C slave<\/span><\/h1>\n
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Let\u2019s do the I2C master and slave communication exercise in order to understand the master receiving data from the slave. <\/span><\/p>\n

Exercise:<\/b><\/span><\/p>\n

When a button on the master is pressed, the master should read and display data from Arduino slave connected. First, the master has to get the length of the data from the slave to read subsequent data from the slave.<\/span><\/p>\n

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  1. Use I2C SCL=100KHz (Standard mode).<\/span><\/li>\n
  2. Use internal pull resistors for SDA and SCL lines.<\/span><\/li>\n<\/ol>\n

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    Things you need for exercise:<\/b><\/span><\/p>\n

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    1. Arduino board, which acts as a slave device.<\/span><\/li>\n
    2. ST board, which acts as a master device.<\/span><\/li>\n
    3. Some jumper wires to connect I2C pins.<\/span><\/li>\n
    4. Breadboard<\/span><\/li>\n
    5. 2 Pull up resistors of value 407K<\/span>\u03a9 (only if your pin doesn\u2019t support internal pull-up resistors)<\/span><\/span><\/li>\n<\/ol>\n

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      1. Circuit connection for this exercise is as shown in Figure 1.<\/span><\/p>\n

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      Figure 1. Circuit connection for I2C master and I2C slave communication.<\/span><\/figcaption><\/figure>\n

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      Connect the ST board to the Arduino board through I2C pins and data will be read from the slave to the master. Then the master has to print the received data over the semi hosting.<\/span><\/p>\n

      Figure 2 shows the connection of the Arduino board with the ST board SPI pins. Don\u2019t use the PB9 here; instead, use PB7 because we have faced some issues with the PB9 in our previous exercise.<\/span><\/p>\n

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      Figure 2. Connection of Arduino board with the ST board SPI pins.<\/span><\/figcaption><\/figure>\n

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      The user button is used to initiate the I2C transactions and also you can use USB logic analyzer if you want.<\/span><\/p>\n

      2. <\/span>Power your Arduino board and download the I2C slave sketch to Arduino, and the sketch name is 002I2CSlaveTxString.ino. In order to perform this exercise, the slave device or Arduino board should be ready with the sketch.<\/span><\/span><\/p>\n

      3. The procedure to read the data from the Arduino Slave is shown in Figure 3.<\/span><\/p>\n

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      Figure 3. Procedure to read the data from the Arduino Slave.<\/span><\/figcaption><\/figure>\n

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