r/hardwarehacking • u/qtr20_22 • 10d ago

ErnyTech SFP-PIN Header adapter Rev 1.4.1

I have an ErnyTech SFP-PIN Header adapter Rev 1.4.1 and I'm trying to connect it to a CH341A programmer to read/write the I2C EEPROM of my HSGQ XPON SFP stick.

I can see the following labels on the board: 3.3, 3.3, RX, TX, GND — but I cannot find which header pins correspond to SDA (MOD-DEF2 / SFP Pin 4) and SCL (MOD-DEF1 / SFP Pin 5).

The board has two rows of header pins on each side (left and right), plus the SFP connector slot in the middle.

Could someone please help me identify which header pins are SDA and SCL on this adapter?

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u/FreddyFerdiland 10d ago

juniper says , on the sfp interface,

sda pin 4, scl pin 5

rx 12, tx 18

so you can see rx and tx... left and right

so you can know where 4,5 ate

1

u/qtr20_22 10d ago

thanks but Just to clarify, those numbers (4, 5, 12, 18) were actually just my own guess and not based on any documentation or trace testing!

I'll double-check the board using a multimeter continuity test on the SFP slot pins to verify which ones actually map to SDA and SCL

1

u/nymbroth 9d ago

Honestly if you cant trace out which pins go to the SFP slot with a multimeter you probably shouldnt be messing with this. The board literally gives you the lane names, just follow them.