Add pull-up resistor to I2C pins ??

Question

Hello everyone !

I'm a new user to the CY8CKIT-042CY8CKIT-042. I'm trying to communicate this kit with a sensor via I2C protocol. To do this, I've connected the SDA and SCL pins of the sensor to the pin P4.0 and P4.1 of the CY8CKIT-042CY8CKIT-042. The next thing I need to do is configurate these pins P4.0 and P4.1 to a pull-up resistor to drive the SDA and SCL line.

I'm trying to do this in the PsOc Creator Software but I don't know how. Can anyone help me with this.

Thanks

BigG · Answer

I'm assuming you wish to use internal pullups. To learn how to configure those, go to the I2C block in your "TopDesign" page and open up the datasheet. This provides you with all the info you need. Find table 1, as this summarises configuring the pins. Then to configure internal pullups just find the "Internal Pullups" section in the datasheet. Within this section it basically tells you to... Add the following code before starting the Component (with SCB_Start()) - don't forget to change "SCB" part to match same name as your I2C block. In my case my block name was simply "I2C". /* Change SCL and SDA pins drive mode to Resistive Pull Up */
SCB_scl_SetDriveMode(SCB_scl_DM_RES_UP);
SCB_sda_SetDriveMode(SCB_sda_DM_RES_UP); (also don't forget to check that the "slew rate" properly matches clock speed as this caused problems with me once before). Hope that helps.

BigG · Answer

I suggest two things. 1. Read through the " I2C APIs " section in the datasheet as this provides a very handy reference of all the functions available for use. There is a very handy summary table, which provides both the "Slave" and "Master" functions (in that order). As you want to read data from a sensor there are two functions: SCB_I2CMasterReadBuf();
SCB_I2CMasterReadByte(); 2. Then to understand how to use these functions, I found that the three I2C master examples provided in PSoC Creator (via the "Find Code Example..." option on the start page and then choosing PSoC 4200 as "Device Family") were sufficient to get me started. These were: I2C_Master_High_Level - this example uses the Read Buffer method I2C_Master_Low_Level - this example uses the Read Byte method I2C_SCB_Master - this example uses the Read Buffer method When you download these examples, it will also download a PDF document, which explains what these examples do. I found the first two example documentation to be pretty good. The 3rd one (I2C_SCB_Master) was not that helpful in explaining the I2C code. Besides documentation, the last example is probably the easier one to get started (IMO) as all the code is in the main.c file. Note, that in my experience, I sometimes found that the sensor documentation and associated I2C methods to get the sensor data may require you to use the low level functionality. But suggest just starting with the high level methods first, as simpler. Hope that helps. PS. check through above examples as they also demonstrate how to check that transmission completed etc.

Add pull-up resistor to I2C pins ??

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