Using CYUSBS234 DVK with external I2C devices

jcsb1994 · ‎Apr 30, 2020

Hi, I bought a CYUSBS234 DVK and used the quick start guide to test i2C-USB bridging functionality, which worked perfectly using the USB Serial Test Utility provided with the CYUSBS234 kit setup. But now I have a few questions before I can start using the kit:

1. I found this page which explains pretty well how to hook up an external i2c device to my kit. But I do not know how I could interface with this device once plugged in. Should I use the USB Serial Test Utility?

2. Actually, I need to understand what happens when you leave the shorts on the jumpers J17 and J21 on the kit, and run the I2C-USB test with the USB Serial Test Utility like I did. Is the software sending data directly to the CYUSBS234 chip (and then where do the jumpers lead??), and then the chip is programmed to exactly retransmit the received bytes via USB?

3. What would happen if I removed the J17 and J21 shorts and connected the external device as explained in the link above? would the utility still reach the chip, and then the signal would be sent via the jumpers to the external device?

4. Is there a way or a software I could use to test sending I2C commands from my computer through USB through the kit and then to an external device? This is basically what I want to do, but I want to understand what is going on in the kit and how i can do that.

Thank you!

Sananya_14 · ‎Apr 30, 2020

Hello,

1. The USB-Serial Test Utility is provided to communicate with the on-board EEPROM as I2C slave. To interface with any other I2C device, you could create your own host application and you could refer to the example applications present with the USB-Serial SDK at- <install directory>\Cypress\USB-Serial SDK\examples\usbserialexample

2. Jumpers J17 and J21 connect to the SCL and SDA lines on the EEPROM (U7) and as you mentioned, the USB-Serial device receives the data from the utility trough USB and writes to the EEPROM over I2C lines. Similarly it reads from the EEPROM and sends the data back to the utility through USB.

3. If you removed the shorts on the jumpers, the I2C lines would no longer be connected to the EEPROM (with pull ups on the lines) so you can directly connect to the SCL/SDA lines of your external device to Pin 2 on the J17, J21.

4. Please refer to point 2, you could create an application to send the commands using the I2C APIs (kindly check the API Guide in the SDK at <install directory>\Cypress\USB-Serial SDK\documentation for more details). The APIs will send the vendor commands to the device via USB and it will perform I2C read or write to your external device as per the API.

Best Regards,

Sananya

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Using CYUSBS234 DVK with external I2C devices

Using CYUSBS234 DVK with external I2C devices

Re: Using CYUSBS234 DVK with external I2C devices