potyo
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potyo said:Hi
Only to avoid misunderstanding, I've checked now the 24FJ128GA's and dsPIC33F
...
On these chips the PGC and PGC pins are also analog inputs?
potyo said:Only to avoid misunderstanding, I've checked now the 24FJ128GA's and dsPIC33F Family's datasheet, and i found these maximums:
Voltage on VDD with respect to VSS........................................................................ -0.3V to +4.0V
Voltage on any combined analog and digital pin and MCLR, with respect to VSS.... -0.3V to (VDD + 0.3V)
Voltage on any digital-only pin with respect to VSS................................................. -0.3V to +6.0V(+5.6V)
Voltage on VDDCORE with respect to VSS............................................................... -0.3V to +3.0V
polymath said:szlovak
If you read thread and understood, you would know that ICD2 monitors target Vdd and modifies +VHH according to the PIC selected, this being transparent to the user.
However, you have given me an idea! - thank you.
be_jouster said:Maybe we can cheat the Mplab by run whole ICD with 3.3V and change a little bit resistor value (voltage divider) for the voltage monitoring so that the Mplab will see the ICD still operate at 5V. I think I need to try it.
Regards.
my research shows:
ICD2 communicates to PIC24 and other devices at 3v3.
Target Power must be from an external supply for 3v3 devices.
The ICD2 can only supply 5V. (my Advanced Transdata PIC-ICD has variable Vdd)
Uncheck the "Power target from ICD2" checkbox in MPLAB.
Connect Debug+Vdd pin to Target +V supply.
ICD2 will sense Target +V supply (RA0).
ICD2 will scale PGC and PGD to the sensed Target +V level (Target+V <buffers> Gnd).
Gobol said:LVC can be used to convert 5V levels to 3.3V, (but how to cope with data transmittion direction... )
maybe using simple 3.3V zeners and transistors would do the trick... ?
Alan69 said:Gobol said:5V i/o ----330--+--3.3V i/o
|
660
|
gnd
LOL of course the no leading spaces messed that up. The lower resistor connects at the + .
Out from 5V the divider gives 3.3 the other side. In to the 5V input sees 3.3V as still a high, the 3.3V ouput just has the extra 660 resistor to ground. Use 2 330 ohms for the 660..
May need to double or triple these values etc for lower powered i/o pins..
That's all the 5V to 3.3V interfacing most things really need. After a few pins though the IC's still make sense..
it's not so easy. PORTC in 16f877(A) is Schmitt triggered, and it doesn't see anything below 3.58V .
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