INCHWORM problem...

asp1987

New Member

• Feb 7, 2008

• #1

Hi,
I am trying to make an Inchworm programmer and would like to know if the circuit connections are proper. The resistance between the pins 16 n 15 of the MAX232 IC is only 650 ohms without inserting max232 and the PIC. These pins are connected to +Vcc and Ground of the PS circuit respectively. The circuit is not applied power. Also its not connected to the computer. I have already soldered the components on to a dot pcb.

Is that normal? Plz help.

 

blueroomelectronics

Well-Known Member

• Feb 7, 2008

• #2

Try appling power without the MAX232 & 16F877A and measure for 5V. There is an LED that may account for the drop.

 

asp1987

New Member

• Feb 7, 2008

• #3

Thanks.
I applied power and got 5V between Vcc and ground.
Then inserted MAX232 IC alone. But now the IC is getting heated up.?!
Is it ok?

 

blueroomelectronics

Well-Known Member

• Feb 7, 2008

• #4

Don't use a MAX232A, use a ST232 as noted in the instruction manual for the Inchworm+ Some MAX232 don't like the larger caps, the ST232 was designed for the bigger caps.

The chip should not get hot.

 

asp1987

New Member

• Feb 8, 2008

• #5

Thanks a lot............It worked. MPLAB communicated with ICD2...

But I replaced the MAX232CPE IC with a MAX232EPE,not ST232. From MAXIMs datasheet,there is not much functional difference between the two. So I guess the other IC was damaged even before I connected it to the Inchworm.

But now the Target Vpp is ONLY 11.66V. MPLAB ICD2 Vpp is 12.06V(from MPLAB). Shouldn't it be atleast 12.5V?

I haven't tried to program any PIC yet. Hope it can....

 

blueroomelectronics

Well-Known Member

• Feb 8, 2008

• #6

11.66 is plenty for all but the oldest PICs. MPLAB will test the value and complain if it's out of range.

 

asp1987

New Member

• Feb 12, 2008

• #7

Thanks bluroomelectronics.. Its working fine.
But one doubt.
When I read the program memory in debugging mode,the program starts at 0x1800-bank3. Shouldn't it start at bank0? When I load the program to pic simulator, some 6000 lines are loaded(entire momory) while my program is only
100 lines or so.
Is this normal?

 

blueroomelectronics

Well-Known Member

• Feb 12, 2008

• #8

Did you include an ORG 0x000 command?

 

asp1987

New Member

• Feb 12, 2008

• #9

No. Could that be the reason? I accessed various banks using 'banksel'. So could it be that the selected STATUS register is the one in BANK3?(or do all status refer to the same STATUS register?) .I am sorry if its a stupid question.

 

blueroomelectronics

Well-Known Member

• Feb 12, 2008

• #10

Yes, try putting it before the first instruction. Don't use the linker though, it uses the CODE command.