Hello! I am trying to connect a 3.3v bluetooth module to a 5v arduino and I need help with the level conversion. Certainly I could just use a voltage divider on the arduino side to bring the 5v down to 3.3v and I believe the 3.3v is high enough on the arduino receive side to register a high level, but I wanted to explore some more sophisticated ways of doing it. I saw the schematic on page 9 (Figure 6 Circuit 2) on this pdf:
http://cxem.net/arduino/download/HC Serial Bluetooth Products 201104.pdf
In the bottom right hand side of the schematic, I feel like there should be a 3.3v pull-up on the UART_RXD to RX_TTL circuit in front of the diode on the UART_RXD side. Why would the pull_up not need to be on there as is shown on the schematic?
http://cxem.net/arduino/download/HC Serial Bluetooth Products 201104.pdf
In the bottom right hand side of the schematic, I feel like there should be a 3.3v pull-up on the UART_RXD to RX_TTL circuit in front of the diode on the UART_RXD side. Why would the pull_up not need to be on there as is shown on the schematic?