MikeRoberts Sorrythese do not work direct with a Raspberry Pi. I made the comment above after driving a PT2314 on a JBL on-time direct with no problems. The problem with the modules relates to their ability to pull the data line low to give the ACK I2C notification. The chips on the two modules I bought had a weak pull down (to only around 1/3V) and hence the Pi did not see this and terminated the transmission. The modules did work with an Arduino Uno that has a lower pull down current (around 0.5ma) compared to the Pi that takes 2ma. So in broad terms these should work with 10k pullup resistors but are unlikely to work with pull-up resistors of 3k3 or less. I normally use 3k3. An I2C voltage level converter should provide adequate pull-down to drive the Pi and may have a low enough pull-down current for the PT2314 modules. Also these modules have 1k resistors in series with the data and clock inputs. These should not be there and make the situation worse. Hence best to short these out (R11 and R12). Mike