TrxAVR introduction

TrxAVR code has been updated (26th June 2015) to operate with Star 4 by Ian G3VPX and Jonathan GW2HFR

(Initially with Hobcat version 1.101 and TrxAVR 1.7)

TrxAVR

is a PCB containing an Atmel ATmega2560 processor, a 24LC512 EEPROM and USB, serial, display and other interfaces.
At the time of writing (May 2009):

TrxAVR has been controlling my development TrxAVR-Picastar HF transceiver on-the air for nine months.
Glenn, VK3PE has his single board Combo Picastar on-the-air controlled by TrxAVR-B (see below)
One member of Picastar-users (not me) has used TrxAVR it to control a Hawaiian guitar!

TrxAVR-Picastar

is a Picastar HF transceiver where:

the original PIC16F876 controller has been replaced by a TrxAVR controller driving a graphics display panel or a 40x2 or 20x4 character display.
The TrxAVR board directly drives Picastar DDS, DSP and diode logic boards.
TrxAVR communicates via USB with it's companion Hobcat program on a Windows PC.
A dedicated RS232 port at 38400 baud provides a CAT interface.
Hobcat provides configuration, loader (ie: DSP code and params), SWR meter calibration.
It has a DSP monitor window and a DDS (CAT control) window.

The interconnection drawing gives a good overview of the project's hardware integration.

HobcatSetup.exe

is a 'Wise' installer that does the following:

Installs Hobcat.exe and Hobcat.chm (help) into C:\Program files\hbradios\hobcat on your Windows PC.
Adds hobcat to the start menu and creates a desktop icon.
Create registry entries in accordance with standard Windows conventions
Creates subfolders of ...\hobcat and loads into them:
- TrxAVR source and hex code
- TrxAvrEemem.ini (to be located in your Star folder)
- Schematics, layouts and copper pdfs for TrxAVR and other PCBs for the project
- Default SWR meter calibration data.
Installs FTDI's USB interface, ftd2xx.dll to your \Windows\System32 folder.

HobcatSetup.exe is an installer/updater. You simply download the latest HobcatSetup.exe and run it to install or upgrade.

Atmel ATmega2560 microcontroller

This is 16mhz 100pin surface-mounting microprocessor.
Some key features are:

84 digital I/O pins in 12 ports.
many alternative I/O pin functions including 4 serial ports, 8 ADC inputs, 8 dedicated interrupt lines, I2C and SPI interfaces.
256kbyte program memory, 8kbyte RAM and 4kbyte EEPROM.
a superb PC based programming system/development desktop (free of charge, language = C)
USB programming hardware.

ATmega2560 datasheet

TrxAVR-A PCB

The original TrxAVR has been named: TrxAVR-A. Its dimensions are 124 x91mm.

TrxAVR-A topside view (bottom in Pad2Pad layout design files). Top-left is FT245R USB chip and USB connectors.
10-way programming socket bottom left now replaced with a 6-way socket.

TrxAVR-A bottom side (top in Pad2Pad layout design files). ATmega2560 chip and adjacent SMD crystal.
(Some of the decoupling capacitors shown here were removed during later development.)

Link to schematic:

TrxAVR schematic

Please note: the schematic doesn't make it clear which I/O lines should have decoupling capacitors.
This omission will be addressed soon. The above image is misleading in this respect as it is from earlier in development.

Layout drawings are in a subfolder of C:\program files\hbradios\hobcat if you download and run hobcatsetup.exe.

The layout of TrxAVR-A is designed for home construction of the PCB (large vias which are not used for component pins).
I/O connections from the processor in the centre of the board radiate out to 0.1 inch connectors with very few crossovers.
The connections are grouped with port and function allocation according to the needs of a Picastar or other HF transceiver.
The schematic is labelled accordingly, and labelling corresponds to the operation of the TrxAVR-Picastar software.
(Pin function can of course be changed with other software.)

TrxAVR's specific provisions include the following:

A FT245R USB interface chip (manufacturer FTDI).
At a cost of under 3ukp, this excellent product encapsulates all the needs of USB device connectivity.
This includes the configuration EEPROM containing the device identification information.
FTDI's free download site provides a PC based configuration program and an interfacing dll with example coding in Delphi and C.
A ST232 RS232 chip for two of the serial ports. One of these communicates with Picastar DSP.
A 10 way connector to a 5x5 push-key matrix
(In TrxAVR-Picastar, this provides for a familiar 4x3 Picastar keypad plus other keys, some of which are menu-definable.)
Two 7805, 5v regulators, one for on-board logic and one for display logic and LED illumination.
Display interface = 8bit data port + control signals.
24LC512 EEPROM- This holds DSP code and parameters exactly as in Picastar. It also holds SWR calibration information.
UDN2981AT 12v relay driver (not used in TrxAVR-Picastar)
Standard 6pin AVR chip programming socket.
Up to 8 analogue inputs. In TrxAVR_Picastar, these are used for:
- Forward and reflected power,
- Two menu assignable DSP parameter control pots
- One optional graphics touch panel.
Two phase/quad rotary encoder inputs.
Each has an interrupt input (phase), a standard digital input (quad) and 0v and +5v conveniently grouped.
(In TrxAVR-Picastar, these are used for a high resolution tuning encoder and an obligatory, low resolution 'menu encoder'.)

Encoders8

This is a separate PCB containing a further ATmega2560 microcontroller chip
It connects to up to eight low resolution rotary encoders.
Its output is a 0/5V serial data stream with a short data messages for each encoder movement.
The messages are of the form $3+01. This particular message means encoder 3 increment by one.

Encoders8 is an option to TrxAVR-Picastar. It provides for eight rotary encoders, each of which can be menu-assigned to control a DSP parameter.

Ian's original Encoders8 (Dimensions 73 x 43mm)
(Apologies for the pock-marked photoboard etching....
solved later by passing film through inkjet twice... Thanks to Johann, DK1CS for this idea)

see Encoders8 for more detail.

TrxAVR-B

is a commercially manufactured PCB that combines TrxAVR and Encoders8.
Its dimensions are 80 x 68mm.
It is a very compact board and so not suitable for home etching of the PCB.
It was designed specifically to work with the single board Picastar of Glenn Percy, VK3PE.
It has IDC ribbon cable connectors that match the PicNmix and other connectors of the single board Picastar.
Chris Stake did the board layout and Glenn had a small number of the boards manufactured.

End of May 2009:

- Chris has a working TrxAVR-B.
- Glenn has his Combo single board Picastar on-the-air controlled by TrxAVR-B with a 20x4 character LCD display.
http://www.carnut.info/singleboard/TrxAVR/vk3pe/TrxAVR_vk3pe.htm

Our 320x240 graphics display motherboards have duplicate connectors:
- IDC connectors matching TrxAVR-B
- 0.1 inch SIL connectors for TrxAVR-A.

TrxAVR-B of Johann, DK1CS

August 2009

Glenn, VK3PE, completed the design of a PCB panel containing:

An enhanced version of TrxAVR-B with touch panel drive electronics
An eighteen button keypad
An 8 button keypad
A serial programmer board for use with PonyProg
An interconnection board

120 of these PBC set have been ordered and delivered.

August 2009
Ian G3VPX and Gerard VK3CG have working 480x272 colour TFT displays
Gerard is now on board as another programmer. Ian doesn't feel so lonely with this task !!
(Chris Stake has also done some programming work)

November 2009
The new TftAVR project uses an Epson S1D13781 controller with an Atmel ATxmega128
processor to drive a low cost TFT colour panel.
Glenn, Chris and Geratd have developed this I2C driven display as a direct replacement
for the expensive EA TFT colour display. Gerard has done a mgnificant job on the
programming. Design for a production board is underway.

TrxAVR-Picastar home page