![](templates/subSilver/images/CCSLogo.jpg) |
![CCS C Software and Maintenance Offers](templates/subSilver/images/forumAd6.jpg) |
View previous topic :: View next topic |
Author |
Message |
YulL
Joined: 29 Sep 2004 Posts: 39 Location: Paris (France)
|
always +2V on my RC7/RX Pin??? |
Posted: Wed Sep 29, 2004 9:03 am |
|
|
Is it normal : +2V on RC7 with PIC16F873???
...
It is connected to my MAX232 on the R2out Pin (9) |
|
![](templates/subSilver/images/spacer.gif) |
Ttelmah Guest
|
Re: always +2V on my RC7/RX Pin??? |
Posted: Wed Sep 29, 2004 9:22 am |
|
|
YulL wrote: | Is it normal : +2V on RC7 with PIC16F873???
...
It is connected to my MAX232 on the R2out Pin (9) |
Simple answer.
No.
This input is a Schmitt input, so requires to be driven to 0.8*Vdd, to be seen as 'on'. The Max232, normally happily does this. Disconnect the pin from the track (if the chip is socketted, bend it out), and verify the voltage on the pin, and on the socket. It sounds as if something else is shorting the pin, preventing it being pulled properly up, or as if your software is not configuring the pin properly, and it is trying to operate as an output, or that the MAX232, is not receiving it's 5v supply.
Best Wishes |
|
![](templates/subSilver/images/spacer.gif) |
asmallri
Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia
|
|
Posted: Wed Sep 29, 2004 9:28 am |
|
|
The PC received data from the PIC so the problem will not be the 5 volt supply. It is most likely two outputs driving in opposite directions |
|
![](templates/subSilver/images/spacer.gif) |
Ttelmah Guest
|
|
Posted: Wed Sep 29, 2004 10:29 am |
|
|
asmallri wrote: | The PC received data from the PIC so the problem will not be the 5 volt supply. It is most likely two outputs driving in opposite directions |
Don't be quite so sure about this. :-)
I have seen exactly this behaviour, when a designer had connected the MAX232, to 3.3v, instead of 5v, it ran for transmit, but gave a very low receive voltage. This is why I suggested the possibility...
However I see in another thread, that the poster has traced it to incorrect wiring round the MAX232 itself.
Best Wishes |
|
![](templates/subSilver/images/spacer.gif) |
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|