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Version: **Question: How can you connect an external I²C device to the CYUSBS234/236 DVK?Answer:

The CYUSBS234 development kit (DVK) has one serial communication block (SCB) that can be configured as I²C. The CYUSBS236 DVK has two SCBs (SCB0 and SCB1) that can be configured as I²C. By default, the I²C lines of the SCBs on both of the DVKs are connected to the on-board EEPROM(s) through jumpers (J17 and J20 for CYUSBS234; J17, J20, J24 and J25 for CYUSBS236). The I²C pins for SCB0 and SCB1 are available on the development board jumpers. The following table provides the details on the locations of the I²C pins available on both of the DVKs.

Table 1. I²C Pin Mapping

                                                                                                                                                 

	CYUSBS234		CYUSBS236
	SCB		SCB0		SCB1
	On Board     EEPROM	External I2C device	On Board     EEPROM	External I2C     device	On Board     EEPROM	External I2C     device
SCL	Short Pin No:2     and 3 of J17	Remove the short     present on J17.     Connect the SCL     line of the external     I2C device to     Pin No: 2 of J17	Short Pin No:2     and 3 of J17	Remove the short     present on J17.     Connect the SCL     line of the external     I2C device to     Pin No: 2 of J17	Short Pin No:2     and 3 of J24	Remove the short     present on J24.     Connect the SCL     line of the external     I2C device to     Pin No: 2 of J24
SDA	Short Pin No:2     and 3 of J20	Remove the short     present on J20.     Connect the SDA     line of the external     I2C device to     Pin No: 2 of J20	Short Pin No:2     and 3 of J20	Remove the short     present on J20.     Connect the SDA     line of the external     I2C device to     Pin No: 2 of J20	Short Pin No:2     and 3 of J25	Remove the short     present on J25.     Connect the SDA     line of the external     I2C device to     Pin No: 2 of J25

You can connect the SCL and SDA lines of the external device to the pin numbers shown in Table 1.

Please note that the pull-up resistors on the I²C bus are connected nearer to the on-board I²C EEPROM (as shown in Figure 1) and hence will get disconnected when the jumper shortings are removed. When you interface an external I²C device to the CYUSBS234/236 DVK, ensure that the pull-up resistors are present on the I²C lines of the external device.

Figure 1. I²C Connection