Hexabusplugjtagprogramming

The HexaBus devices do not offer a simple ISP-style interface for programming - we use the much more powerful JTAG interface. You need a JTAG-capable programmer for this. We have successfully used these two devices:

1. The Atmel JTAG ICE MK2. This is definitely a very professional programmer that can also program a lot of different chips. The drawback is its price point: at approx. 250 Euro, its not cheap. Stay away from the newer JTAG ICE MK3 - Atmel has not released its communication protocol, so it cannot be used with avrdude or any other free software.
2. The Atmel AVR DRAGON. This is a cheap Atmel JTAG interface - it can be bought for around 50 Euro. It consists of a single PCB, so you need to add a USB cable and a 10-pin ribbon cable, but still its much cheaper than the JTAG ICE MK2. However, the devices are said to be sensitive to static electricity - see the mikrocontroller.net page (German) for an in-depth discussion.

Use JTAG to program the HexaBus Plug

The plug offers a combined JTAG- and Serial interface connector. It is the micromatch connector on the left side of the low voltage PCB. My deluxe development setup looks like this:

It features a JTAG adapter and the serial interface, as described on the Hexabusplugserialinterface page. Both connectors are exposed on a small hand-soldered PCB. The schematic for this is simple:

Using AVRDude

The ATMega1284 can be programmed using the JTAG interface and avrdude. You can use

$ /usr/local/bin/avrdude -c jtag2 -P usb -p atmega1284p -U flash:w:Hexabus-Socket.hex -F 

to program the device. You need to consider two points here:

1. The atmega1284 has currently no definition in the avrdude.conf. Fortunately, it is almost identical to the definition of the atmega1284p, but has a different device signature. Either you patch your avrdude.conf or use the -F paramater (as above). This will disable the signature check (but please be careful!)

2. Make sure you use a recent version of avrdude. The hex file needs more than 16 bit for adressing, which is only implemented in newer versions of avrdude. I am using 5.10, which is working fine. See also [https://github.com/mysmartgrid/hexabus/issues/9] for an in-depth discussion.