Forums

K149 programmer

Started by laughty g May 26, 2003
Hi,
Recently I have just constructed a K149 programmer to program the 93LC46B serial eeprom. I have removed the USB portion.
 
I have read on the website that this programmer is capable of programming 16F877 chip too. However, although my programmer board can be detected, the program keeps prompting "the programmer does not recognise the 16F877 chip" error.
 
Would anyone please help me solve this problem. The website is http://www.qkits.com/serv/qkits/diy/pages/QK149.asp
 
Thanx a million :p
Glen

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Hello Glen;

I have a K149 too, I have seen this error with other devices, but it
happens when the device is not selected from the drop down menu.

I realize that this might be stating the obvious and is probably not
your problem, but as I saw your post and have seen that message
before, I thought I would state the obvious anyway !!

Cheers

PeterC



My Rev. B K149 should be here any day now, I'll see what happens with the 16F877A chips that I have.

But I have a couple of broader questions for the group.

Virtually every programmer design I've come across on the net uses one of the open collector drivers (7407, '06, '05, etc.) to drive a "pass transistor" for both the VPP and VDD to the chip being programmed. Why? The oc driver chip by itself, can source and sink the 200uA that the MCLR pin draws. And each data sheet makes a point of stating that no significant current is drawn by the MCLR pin during programming.

The only data sheet which shows the current draw during programming for the VDD supply is the 16F84A, and it shows a max of 50mA during programming, so I can understand the need for the transistor to source this supply. Why are there transistors to drive the VPP ?

My second question is about the floating or otherwise connected RB3 and RB4 pins in most programmer designs (the K149 pulls down these pins) that program the 16F87x and 16F62x chips. If these pins are high during programming mode the chip will go into a low voltage programming mode, does this cause flaky operation for most programmers since they use the high voltage programming mode?

thanks,
dave.

In a message dated 5/26/03 8:29:50 PM Pacific Daylight Time, l...@yahoo.com.sg writes:

...I have read on the website that this programmer is capable of programming 16F877 chip too. However, although my programmer board can be detected, the program keeps prompting "the programmer does not recognise the 16F877 chip" error....






Well, the voltage at the output of the '06 is well above 5V when the
input is logic 0. With no current flow through the base of the pass
transistor the voltage will be about 13V. A totem pole TTL (or even
CMOS) device can't do this. Given that 1 or two devices require this
it is easier to do them all this way (OC).

I think there is a revised programming requirement on newer devices
that requires RB5 and RB3 be pulled down. This may be the big change
in programmers for the newest devices. --- In , dkbovaird@a... wrote:
> My Rev. B K149 should be here any day now, I'll see what happens
with the
> 16F877A chips that I have.
>
> But I have a couple of broader questions for the group.
>
> Virtually every programmer design I've come across on the net uses
one of the
> open collector drivers (7407, '06, '05, etc.) to drive a "pass
transistor"
> for both the VPP and VDD to the chip being programmed. Why? The oc
driver chip
> by itself, can source and sink the 200uA that the MCLR pin draws.
And each data
> sheet makes a point of stating that no significant current is drawn
by the
> MCLR pin during programming.
>
> The only data sheet which shows the current draw during programming
for the
> VDD supply is the 16F84A, and it shows a max of 50mA during
programming, so I
> can understand the need for the transistor to source this supply.
Why are there
> transistors to drive the VPP ?
>
> My second question is about the floating or otherwise connected RB3
and RB4
> pins in most programmer designs (the K149 pulls down these pins)
that program
> the 16F87x and 16F62x chips. If these pins are high during
programming mode the
> chip will go into a low voltage programming mode, does this cause
flaky
> operation for most programmers since they use the high voltage
programming mode?
>
> thanks,
> dave.
>
> In a message dated 5/26/03 8:29:50 PM Pacific Daylight Time,
> laughtyg_techfo@y... writes:
>
> > ...I have read on the website that this programmer is capable of
> > programming 16F877 chip too. However, although my programmer
board can be detected, the
> > program keeps prompting "the programmer does not recognise the
16F877 chip"
> > error....
> >