I have a CJMCU-204 4-Port USB hub. In addition to 4 type A ports it has a 6-pin header, labelled VCC, DMU, DPU, GND (which may be for a possible 5th port) and SDA & SCL.

The board's chip is labelled "FE1.1s usb 2.0 hub LV3P908810276C".

How are SDA and SCL used? I've searched and found places that sell the hub, but none have any details or documentation.

Thanks,
Jim

 

It's an interesting puzzle. I also searched, and thought that I went pretty deep with Google Translate and the like - nothing. It is being sold as a controller and more commonly as a hub - for a RPi , but even for Arduino. I didn't even find a single comment about its use which suggests that it functions ok as a simple hub without further need for documentation.

There is a lot of information on the chip used, FE1.1s usb 2.0. You can buy as many as you might want - https://www.aliexpress.com/wholesal...120316&site=glo&g=y&SearchText=FE1.1+S&page=2

You can visit the manufacture's site http://terminus-tech.com/English/products.html and you can get some data sheets https://cdn-shop.adafruit.com/product-files/2991/FE1.1s+Data+Sheet+(Rev.+1.0).pdf / http://terminus-usa.com/pdfs/FE1.1s (B) Product Brief 1.0.pdf / http://elinux.org/images/e/ee/FE11-datasheet.pdf

A general search on the chip will also produce some schematics but none that I found with SDA/SCL lines or any indication of I2C control.

But there certainly are USB Hub chips that do have I2C control (like this one from Cypress http://www.cypress.com/file/129946/download).

Since the FE1.1S seems to have a ROM, it is not out of the question that there is some kind of enabling or switching or something that is under I2C control - but I don't see where it is at. You could hook it up to an Arduino and run an I2C scanner and see if they are even active - the worst you will do is brick the board and anything connected to it

SDA/SCL could simply be mislabeled or for some version of the board using a different chip - who knows?

Please let us know if you find out more.

 

Thanks Raymond,

The Adafruit link has what I was looking for. The chip uses i2c to read configuration data from an optional EEPROM that it can report to an upstream host, including Vendor ID and Product ID. The check for the EEPROM is made each time the FE1.1s is reset, so I suppose the EEPROM could be replaced with a chip with a bit of logic to report a different version under differing conditions.

The other 4 header pins are for an alternate upstream host connection.

 

Thanks Raymond,

The Adafruit link has what I was looking for. The chip uses i2c to read configuration data from an optional EEPROM that it can report to an upstream host, including Vendor ID and Product ID. The check for the EEPROM is made each time the FE1.1s is reset, so I suppose the EEPROM could be replaced with a chip with a bit of logic to report a different version under differing conditions.

The other 4 header pins are for an alternate upstream host connection.

Ahh, now I see it on page 6 of that data sheet.