John, VK2ETA, has implemented a range of changes in Ian KD8CEC’s software targeted at portable operations (the software can be downloaded here in the files section of the BITX20 IO Group).
VK2ETA Software modifications to KD8CEC firmware
The scope of these modifications is described below:
Options for various features – These can be turned on or off. Key objective is to be able to customise the rig based on your needs and unfortunately on the restricted memory size of the Nano. So not all features can be selected at once. Choices, choices…
ATU control – A servo-based L-Network ATU. The communication between the Raduino and the ATU Arduino is via I2C. There is a separate sketch for the ATU Arduino (Nano or Pro-mini). ATU operating mode can be set to OFF, Manual as in on-demand, or auto-RX meaning that it pre-tunes based on historical data on a change of band and after first change of dial frequency (for a quick scan of the bands). It uses the EEPROM data of the closest stored frequency for pre-tune or tune on-demand to accelerate the tuning process.
Handsfree microphone/headphone – Using an Android style 3 rings (TTRS) handsfree earpieces/mic combination, with 1 or 3 buttons (Play/Pause, +, -), the PTT is controlled by Play/Pause as toggle, and I use long presses on + and – as respectively pre-tune and smart-tune of the ATU. Short + or – presses could be used for frequency up and down. Requires a very simple hardware mod to free-up A6 (see below).
S-meter measure and display – using analogue input A7 from an 2N7002 based AGC or a MAX9814 circuit or any other for that matter.
Software based AGC range extender – to augment (as in double or triple) the dynamic range of an audio AGC. This uses the slope of the 1st If filter at 45Mhz to attenuate the Rx signal when the audio AGC reaches its limit. Adds over 50dB of dynamic range.
Forward power and SWR measure and display – Currently assumes that the ATU is providing that info over I2C. Otherwise could be adapted with a pair of analogue inputs for measure. See the excellent NT6D design on the wiki.
Options for displaying the S-Meter, SWR and forward power – in either easy to see “fat” bars with no number, or “skinny” bars with more text and numbers.
Enable a “Memory mode” – selectable by menu, which cycles through all the populated memories (channels). Dial lock also locks the change of channels.
Made some rarely used or once-off functions as options – to recover program memory after initial tuning and allow for more options to be selected.
Fixed some issues with the IF-shift option – Ian has resolved these in his new V1.06 and later releases. Two issues were present: IF-shift in USB would change the receive frequency and it was applied to TX as well. Now applies to Rx only.
Hardware modifications required to use VK2ETA software mod
The only required hardware mod is to connect the CW key input to the PTT. Since in Ian’s software we select the mode by menu, there is no need to have a separate analogue input tied-up for the CW key. This frees-up analogue input 6 for use by other functions like the handsfree option above.
Still to come
John plans to apply Ian’s improvements in v1.06, especially the CW transmit frequency option and if possible the WSPR beacon mode (as a further add-in option).
How to use VK2ETA software
Download the zip files, and unzip these in your Arduino sketches folder. Edit the ubitx_20 options sections, using #define for enabled and #undef for disabled.
Perform a CTRL-R to compile and check how much memory is used. If you go over the limit, a warning is issued. Providing you have enough memory to run the software, upload the sketch to the Arduino.
John has uploaded both the Raduino as well as the Arduino sketch for the ATU and SWR measurement. They can be found in the folder “Variations on Ian Lee’s Software (by VK2ETA) + ATU sketch”.
