The CM108 and similar USB audio chips which are used in many low cost USB sound interfaces have some user controllable GPIO pins. Although these aren't usually connected it is possible to modify some of these interfaces to make this available for use as a PTT function or to build an interface from scratch using these devices.

2022年4月19日 · The CM108 (which is actually the part number for the USB chip) is a USB audio interface with I/O (inputs and outputs) that can be used for connecting a radio to a Raspberry Pi. I am not going to go through all the soldering and wiring …

Note that, while some CM108 sound cards permit the PTT signal to be derived from GPIO3 on pin 13 of the CM108, not all CM108 sound cards actually expose this pin. In this case, a simple VOX circuit can be used for PTT instead.

2020年5月9日 · Notes on my CM108 adventures. PTT and COS polarity (Active HI vs. Active LOW) are determined by your particular software and OS. If you cannot change them in software, you must use other discrete components to invert the signal. If your radio hangs in TX see if the condition persists with the USB unplugged.

A simple hacked-together PTT library for CM108 USB soundcards. This is code from the Hamlib, which I simplified and made work standalone. It has a very hackish style and should not be used for anything but testing as it may have all kinds of weird bugs. To build a test-tool which just pushes the PTT button for one second enter: make

cosplay.sh is a command line tool that takes a media file (or pipe) and plays its audio content to a radio transceiver with a CM108 PTT interface. It can be used for automatic ident, allstar nodes, repeater control, etc. Default PTT delay and GPIO number are chosen to work well with the BF-888S and the commonly found homebrew CM108 mod with an ...

2013年5月9日 · This project will adapt the CM108 fob to be compatible with a standard Echolink-type interface. My interface was built to use a serial port, DB9 pin 7(RTS) for PTT, pin 8(CTS) for COS, and pin 5 for ground. Of course, you could also decide to use the information here to modify a Startech USB fob for PTT, COS and/or GPIO via USB.

2024年9月28日 · The GPIO ports of the CM108 are accessed by the OS as a USB HID device. Some ham radio applications (like fldigi, VARA, Dire Wolf etc.) can acces the GPIO (PTT) pin of the sound chip directly. For applications that can only do PTT by keying the RTS line of a (virtual) COM port use "CAT7200", a small tool written by J. Wiseman G8BPQ that is able ...

2022年6月11日 · Software TNC Direwolf 在最新的版本 ver1.6 / 開發版 ver 1.7 支援以 USB soundcard cm108 芯片的 gpio 作為 ptt。 那就可省回一個寶貴的 USB port 和 USB to serial adaptor，以至用 audio 隔離火牛做的 sound modem。 接線簡化了，成本也降底了。 我希望以這個方案為基礎，玩盡 direwolf sw tnc 各功能。 ok，首先要變一個 cm108 usb sound card 附 ptt 功能的手指出來。 國外網站的資料，多是土炮到暈的製作， I don’t like it。 那唯有靠我對線路的 …

2023年11月15日 · It might be helpful if you could run the 'cm108' utility in a Terminal window and post the results here. which will toggle PTT on and off at 1 second intervals, and then see if your device is triggered correctly.