New (and simpler) version of BOB-SCAP (01-02 2015 French Elektor)
This is a simpler version of BOB-SCAP, backup AVR programmer. There is no added hardware, the signals are reversed by software.
In the January-February 2015 French Elektor magazine, I published an article called BOB-SCAP. This article presented a way to use an Elektor BOB-FT232R to make a simple backup AVR programmer like SCAP described there.
Since SCAP was directly connected to a physical serial port, in order to make BOB-SCAP work it was necessary to add a 74(LS)04 to reverse the signals between the BOB-FT232R and the AVR programmer socket.
In the meantime, I built another AVR programmer interfaced with a BOB-FT232R and in reading avrdude.conf file, I realized that it was actually possible to reverse the signals in the software, thereby eliminating the need of adding hardware.
Consequently, BOB-FT232R in itself can be a simple backup AVR programmer.
The only difference is then found in the avrdude.conf file.
For the hardware reversed signals, BOB-SCAP definition in avrdude.conf was actually the same as SCAP:
Since SCAP was directly connected to a physical serial port, in order to make BOB-SCAP work it was necessary to add a 74(LS)04 to reverse the signals between the BOB-FT232R and the AVR programmer socket.
In the meantime, I built another AVR programmer interfaced with a BOB-FT232R and in reading avrdude.conf file, I realized that it was actually possible to reverse the signals in the software, thereby eliminating the need of adding hardware.
Consequently, BOB-FT232R in itself can be a simple backup AVR programmer.
The only difference is then found in the avrdude.conf file.
For the hardware reversed signals, BOB-SCAP definition in avrdude.conf was actually the same as SCAP:
# --------------------------------------------------------------------------------
# BOB - Serial Cheap AVR Programmer (BOB-SCAP)
# reset=rts sck=dtr mosi=txd miso=dcd
programmer
id = "bob-scap";
desc = "BOB - Serial Cheap AVR Programmer, reset=rts sck=dtr mosi=txd miso=dcd";
type = serbb;
reset = 7;
sck = 4;
mosi = 3;
miso = 1;
;
# --------------------------------------------------------------------------------
For the programmer I am proposing now, named BOB-INVERSE-SCAP, the definition in avrdude.conf is as follow (note the tilde in front of each signal, except ret that is not used anyway):
# --------------------------------------------------------------------------------
# BOB INVERSE - Serial Cheap AVR Programmer (BOB-INVERSE-SCAP)
# reset=rts sck=~dtr mosi=~txd miso=~dcd
programmer
id = "bob-inverse-scap";
desc = "BOB Inverse Serial Cheap AVR Programmer, reset=rts sck=~dtr mosi=~txd miso=~dcd";
type = serbb;
reset = 7;
sck = ~4;
mosi = ~3;
miso = ~1;
;
# --------------------------------------------------------------------------------
The way of using BOB-INVERSE-SCAP with avrdude is exactly the same as using BOB-SCAP and is described in the article.
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