An ICSP mystery...
Interesting.... geeky.... but interesting...
There has been 'indication' with this latest rev of the brake board that in circuit programming seems to be, well... a bit of an issue.
I can program the device ONCE...
And though I am supposed to be able to REprogram it... after the first time, thats IT, re-programming does not work. Which of course, begs the question:
WHY???
Other strangeness noticed:
Erasing the device results in wiped program data, wiped eeprom data, wiped ID bits, BUT.... the config bits are often INVERTED of what they were programmed as.
I am confidednt that they were programmed correctly when programmed the first time, but erasing them does not work properly. RE-programming results in messages that the device is not blank.
Okay, without making a drama out of this, the problem has been traced to the fact that I am powering the device from an external power supply (i.e. not the programmer's power).
I, in fact, tested that with the device plugged right into the programmer, it programs... and with the device still plugged into the programmer, and the Vdd pin lifted, and connected to a nice clean 5V power source (grounded at the Vss pin of the chip) .. it does NOT. (except for that first time)
The only two things that come to mind are:
1) A ground loop caused by the wall wart coupling through the 115V line back through the switch mode power supply.
and
2) The device goes into a 'strange' state when power has been applied to it well in advance of the attempt being made to program it.
We will see... I submitted a ticket to Microchip asking if they had any ideas.
... yet again: *sigh* .....
There has been 'indication' with this latest rev of the brake board that in circuit programming seems to be, well... a bit of an issue.
I can program the device ONCE...
And though I am supposed to be able to REprogram it... after the first time, thats IT, re-programming does not work. Which of course, begs the question:
WHY???
Other strangeness noticed:
Erasing the device results in wiped program data, wiped eeprom data, wiped ID bits, BUT.... the config bits are often INVERTED of what they were programmed as.
I am confidednt that they were programmed correctly when programmed the first time, but erasing them does not work properly. RE-programming results in messages that the device is not blank.
Okay, without making a drama out of this, the problem has been traced to the fact that I am powering the device from an external power supply (i.e. not the programmer's power).
I, in fact, tested that with the device plugged right into the programmer, it programs... and with the device still plugged into the programmer, and the Vdd pin lifted, and connected to a nice clean 5V power source (grounded at the Vss pin of the chip) .. it does NOT. (except for that first time)
The only two things that come to mind are:
1) A ground loop caused by the wall wart coupling through the 115V line back through the switch mode power supply.
and
2) The device goes into a 'strange' state when power has been applied to it well in advance of the attempt being made to program it.
We will see... I submitted a ticket to Microchip asking if they had any ideas.
... yet again: *sigh* .....