casesconnectormountpcb
I opened a small router and hooked up 2 wires on the PCB (to catch the serial data). That works fine.
Now I'm looking for a way to make a small (tiny) connector in the enclosure, so for future use i can easy attach a connector.
My question, in the land of of a billion connectors, what would be a good small (female) connector, panel mount, max. 5×5 mm?
Many thanks.
If "daisy-chaining" means that data will come in on "I2C0" and be repeated out "I2C1", you shouldn't have many problems other than your slaves being too busy responding to interrupts to measure anything.
"Daisy-chaining" could also mean bussing them.
In either case, consider raising your voltage and/or using a buffer/line-driver (at least between the longest runs). This approaches a redesign of RS-232.
Simple and might be good enough:
simulate this circuit – Schematic created using CircuitLab
I purchased a KILL A WATT (tm) model P4460 energy meter, then curiosity made me open it up. The male "prong set" and the female "jack set" face to the back and the front of a vertical PCB board with buttons and LCD display.
They are soldered directly to the PCB.
The input and output pins are vertically offset about 2 cm with conductors joining the neutral to neutral and the earth to earth.
The hot conductor contains a shunt for all the circuitry.
On this unit the male prongs extend through the case to form the male power plug (North American style). The female prongs line up with holes in the case to form a power receptacle.
I have seen that most of the power-consuming small devices use a 2-piece setup like your photo. The higher currents of your device might need a 1-piece prong like the KILL A WATT. Good Luck!
Best Answer
The CP2102 USB to UART Bridge has an unbalanced 3.3V interface so you should be connecting ground in addition to the TX and RX lines. Using a shielded cable probably isn't a bad idea although at fairly standard low baud rates such as 9600, 57600 etc noise immunity is fairly good so you may not have to worry a lot unless the application is critical or you're in an electrically noisy environment. For test purposes I've run 3.3V TTL serial lines over a few meters of unshielded cable without problems.
A connector I've used in the past that is quite robust and offers panel mount in a small form factor is the Binder 709/719 series. The 3-way panel mount part number can be found at Element 14: Binder 09 9750 30 03. They are a little larger than your specifications and not exactly dirt cheap but are very easy to solder to, here's an indicative photo that shows the 4-pin variety:
Your idea of using a 2.5mm audio jack is probably also worth considering although you need to be aware that while inserting the plug some pins can be temporarily shorted. The RX line being shorted to ground or TX won't matter but you should take care with the TX line at each end. Without specific details of the hardware at each end it's hard to know for sure but a 3k3 resistor in series with the TX line at each end will limit the current to 1mA which should be safe for most devices I can think of.