I am trying to interface the 8-pin bluetooth module Promi-ESD-02 with the Keil MCB2140 ARM7 board. The bluetooth module communicates with the MCU using UART (so I need to connect it to RxD0, TxD0 pins of the MCU).
My problem is that there are no jumpers for the RXD0, TXD0 or RXD1, TXD1 so that I can safely remove the MAX563 IC (that converts +/- 12V to logic levels) from the circuit. In other words, I can't connect the bluetooth module directly to the MCU pins.
I was thinking about Software UART. What other options do you recommend? I'm a student working on this project and I don't have price/performance limitations, or any other hw/sw tradeoffs restrictions.
P.S. : I've already written a UART0 module - COM0, so it there a possibility to use that?
Schematics: http://www.keil.com/mcb2140/mcb2140-schematics.pdf
Thank you
You do not (!) want to use a software UART. If you know how to get one to work, you would not need any help from this forum in the first place.
Either lift the single pin sending data from the transceiver to the processor for the specific UART. Or get another transceiver to convert back from RS-232 signal levels into the suitable logic levels for the BlueTooth device.
Wait a minute. The guy is a student, and his requirements are somewhat different than ours. He needs something that works. Why not implement a software UART, then?
See here - you only need to fill in the missing pieces (timer...) but that should be a no brainer for you:
supp.iar.com/.../
I think the RS232 transceiver approach is likely yo have (far) better chances of success...
It will also be valuable in tests/experiments with a PC...
Thank you for the responses. I think I will try both methods (Serial UART and RS232 transceiver) just to see how it works. Got a MAX3232 so there should be no problem.
Has anyone tried to program the LPC2148 with bluetooth? Can it only be done with a bootloader? Otherwise I need to control somehow RTS and DTR signals (from RS232) used by Flash Magic for in-system programming.