Hi, i am using atmega128 with Bluetooth module HC05. I was having No trouble at all with the communication but reccently a new batch of bluetooth module arrived and with the same configuration when i replaced the new BT with the previous one, it doesn't recieve data properly. I found out the problem and placed a pullup resistor on my microcontroller RX and and Vcc and it sort of worked... My question is that does the BT module have a built in pullup resistor because previously it was working without Pullup resistor but the batch that recently arrive not a single one of them work without pullup resistor. and is there a way to check the presense of pullup resistor in bluetooth module HC05 .
Thanks