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The older AZBox receivers, includ-
ing my Ultra HD, utilize an internal se-
rial interface. You can use it to hook
into the Bootloader and reflash the
firmware. But it‘s not as easy as it
sounds; the internal serial interface
operates at TTL levels (3.3 volts) as
opposed to the 12 volts of an RS232
If you would use a null modem cable
to directly connect this internal serial
interface to the COM port of a PC, a
hardware problem would result.
In a case like this you‘d need a TTL
adapter, something you could find
very inexpensively on eBay for around
2 Euros. It has to do with a USB TTL
adapter that would be automatically
recognized by a PC as a COM port.
This adapter uses the well-known Pro-
lific 2303 chip that is used in most USB
RS232 adapters. The one difference is
that in this case MAX232 comes into
play here for the level conversion.
But I opted for another solution: I
used an old Nokia DLR-2L data cable.
Since I wasn‘t using this cable any-
more, I simply cut off the Nokia con-
nector. Using an oscilloscope I figured
out that the red wire was RX, the green
wire was TX and the black wire as ex-
pected was ground.
An old CD-ROM audio cable for com-
puters provided a suitable connector
for the AZBox; the corresponding wires
just had to be connected together.
After an initial test, I realized I made
a mistake that almost everyone else
makes when it comes to serial trans-
missions: TX and RX naturally have to
have a criss-cross connection. Once
that was taken care of, it then worked
Using Putty, a very well-known free-
ware terminal program, I was able to
access the AZBox Bootloader. It an-
nounced that the firmware was invalid.
This Bootloader is called YAMON (Yet
Another MONitor) and is far more com-
prehensive than standard Bootloaders
of older receivers. It lets you, among
other things, read the RAM memory or
send it to the PC.
Aside from that, you can also delete,
read and program the Flash memory.
Finally, it‘s also possible to start the