I have a old Intel 96 MCU and a Atmel Mega2560 that I need to share the same FTDI USB IC.
When I connect RxD and RxD from both micro to the FTDI, the signals from the Intel 96 are lost. The Atmel has no problems. Testing has shown the signals from the Intel have no power behind them and drop to almost 0 volts. If I fit 470R resistors in the signal lines from the Intel, the signals are 0 to 5 volts as expected. Tried 34R resistor and got weak signals, but not good enough to be excepted by the FTDI. Connecting just the Intel to the FTDI works and get the expected data.
How can I boost the power of the Intel signals. Use two small transistors ?
Ray.
When I connect RxD and RxD from both micro to the FTDI, the signals from the Intel 96 are lost. The Atmel has no problems. Testing has shown the signals from the Intel have no power behind them and drop to almost 0 volts. If I fit 470R resistors in the signal lines from the Intel, the signals are 0 to 5 volts as expected. Tried 34R resistor and got weak signals, but not good enough to be excepted by the FTDI. Connecting just the Intel to the FTDI works and get the expected data.
How can I boost the power of the Intel signals. Use two small transistors ?
Ray.