Starting to communicate

A project log for Philips LivingColors gen1 WiFi addon

Add an ESP8266 to a Philips LivingColors gen1 to control it over WiFi without losing the ability to control it with the remote

StefkuhbStefkuhb 11/12/2018 at 15:560 Comments

Before we can start adding components I have to find out how this system works. I took apart the LivingColors gen1 and found the PCB. It looks like Phillips used a Texas Instruments CC2500 for the wireless communication with the remote and a Texas Instruments MSP430F135 as main controller. It also has 4 high power LED's and each of them has a dedicated driver.

These IC's must be communicating somehow so lets look at the datasheet of the CC2500 which states in the product description "CC2500 can be controlled via an SPI interface". SPI often uses 4 signal lines: MOSI, MISO, SCLK and SS. If I find these lines and hook up a logic analyzer I can look at the data being send and received.

If I look at the PCB I see that there is a pad where no part is mounted named H301 close to the MSP430F135. When I follow these lines to the controller I get the following pins:

DVss (GND)P3.5/URXD0
RSTP3.3/UCLK0 (with a 330R resistor)
TDO/TDIDVcc (2.8Vdc)

The pins RST, TCK, TMS, TDI/TCLK and TDO,TDI are used for JTAG probebly to flash and debug the controller. 

The UCLK, SIMO0 and SOMI0 pins are the MSP430F135 dedicated SPI pins. but I am missing the SS pin! In the datasheet it states that the STE0 pin (28) is used for SS but its not on the pads of H301.

Lets look at the CC2500 datasheet, it states that pin 7 is the CSn (SS) line. if I follow the pcb trace of pin 7  of the  CC2500 it goes to R704 and after that to TP308.

Great! I can solder some wire to the pads to hook up my logic analyzer!