EKG/EMG SHIELD - wrong reference value

[unknow]

Dear Olimex,

I just buyed your SHIELD-EKG/EMG (Rev.C) and created my own app for receiving data pakets. Everything works, but I am doubt about the correct wiring, because "reference" value is not in middle of 10bit resolution (around 512) but somewhere around 280.

My setup:
Arduino Uno (5V powered trought USB port)
Jumped is on 5V pins, D9 and AIN_SEL 1. VREF_E pins are empty.

Is it OK?

Another question. I tryed to get better gain via trimmer, but turning will not bring any changes in signal! Is it OK?

Thank you.
   

[unknow]

Hello,

because I doubted about the functionality of the OLIMEX device I buyed second one EKG shield. It still have (wrong) reference value around 280 (and not around 512 which I saw on YouTube) as first one but it works much better and signal have far less noise (noise amplitude is maybe 3 times smaller). Even when I use them both, the second one show better signal. Because of this I will send first device to dealer (warranty).