A little usage experience

A project log for Amateur Radio CAT/CI-V Interface Adapters

Interface to talk to numerous amateur radios.

BharbourBharbour 05/11/2020 at 19:340 Comments

After using the USB board for a few days, I found that the other USB based UART chip (supporting the GPS receiver) sometimes enumerates before the one in the USB to CI-V interface. I have a 4 RS232 port board from a previous project, but it does not support the DTR signal that powers the RS232 version of the the CAT/CI-V interface. Most radios have a low voltage output available from the microphone connector or accessory connector. The ICOM that I am working with now supplies 8V at a few milliamps. I did a little rip up on the RS232 version and installed an LDO to make 5V out of the 8V and added a connector for the new DC input. The pullup resistor on the output transistor emitter was reduced to 2.7K from 4.7K to get a little bit more output voltage swing on the COM_IO line. I also pulled out the pin jumpering for the handshake pins because I think that they are un-necesary. The new PCB went out to OSHPark on Saturday morning. The schematic for the new design is titled: CIS_to_9Pin_Ext_Pwr in the files section.