BC66-TE-B v2.1 schematics needed

Hello Team,

I’m looking for schematics of this module.
I have problems with I/O-levels, when it is used as a shield for Arduino MEGA 2560.
It seems that BC66-TE-B v2.1 is intended for use only with I/O-levels=3.3V, and there is problem with Arduino communication. I can’t find any jumper for switching I/O-levels neither on the board, nor in the “Rev. BC66-TE-B_User_Guide_V2.1”.
Please, help me.

Thank you !!!

Hi TonyM
Need to switch J302 to MAIN UART TO MCU.

Hi Abner,

Of course, the switch J302 is at position “MAIN UART TO MCU”. And the problem remains.

So, I found the problem after investigating the PCB of v.2.1. This version of BC66-TE-B works only with I/O-levels=3.3V on Arduino interface (connectors J305, J306, J307 and J308) and this can’t be changed to I/O-levels=5V. Arduino MEGA 2560 has only I/O-levels=5V. If you want to connect BC66-TE-B-v.2.1 with Arduino MEGA 2560, you have to use external 3.3V<->5V logic level converters for at least UART RX and TX lines. But there is another problem- missing VCCB=3.3V for U303=TXS0108E (8ch logic level converter 1.8V<->3V, where UART RX and TX lines goes) if you connect Arduino and BC66-TE-B-v.2.1, but not connect USB-cable to PC or 5V. This problem is because VCCB=3.3V on U303=TXS0108E is provided by VDD=3.3V of U301=CP2108 (USB to Quad UART Bridge Controller), so it exists only with 5V on J301.
I’ve made a workaround by soldering a jumper, parallel to diode D201. In such a way, Arduino MEGA 2560 supplies 5V to BC66-TE-B-v.2.1 and I have VCCB=3.3V for U303, but I still have to use external 3.3V<->5V logic level converters for UART RX and TX lines. So you still can’t directly “sandwich” the boards.
My proposal for next revision of the board is to connect VCCB of U303 to VDD of U301 through diode, and also VCCB of U303 to the common point of cathodes of the diodes D200, D201, D204 (5V-common-point) through another diode and a jumper. In such a way, you can “sandwich” the boards directly and don’t need external 3.3V<->5V logic level converters for UART RX and TX lines (at this case VCCB of U303=5V, when the jumper is ON). When you use BC66-TE-B-v.2.1 standalone with USB-cable connected to PC, you have to remove the jumper and will have VCCB of U303=3.3V.

Hi TonyM
Thank you for your valuable comments.