RB4 pic16f627

[krismoly]

hi Folks,

I am experiencing some problems with rb4 on pic16f627.

The pin is configured as an input, however, everytime the pin goes high, it holds the pic in a reset state.

From reading the data sheet I think the pic is entering a low voltage programming mode. I have set the _LVP_OFF in the config word, and still it is entering this mode. the mclr pin is tied to vdd via a 10k resistor. The program runs correctly until rb4 goes hi.

rb4:7 (inputs) are connected to a bcd switch, when a transmit button is pressed this is then sent to a pc via the serial port and is displayed correctly in hyperterminal.

I dont fully understand the datasheet inparticular the term VIHH can anyone help?

Regards
Kris

 

[Pommie]

You can confirm that LVP is disabled by enabling the WPU's and checking the voltage on RB4 (RB4 should be set to input and open circuit). If you see 5V then LVP is disabled. If LVP is still enabled then you need to program the chip using high voltage mode in order to reset the LVP bit. You cannot reset the LVP bit while in LVP mode.

Mike.

 

[krismoly]

sorry I'm new to pics Pommie,

can you explain what you mean by WPU's? I can confirm that rb4 is set to input.

regards
Kris

 

[krismoly]

hi folks,

I seem to have solved problem. it appears as though my programmer (velleman) was causing problem.

I reset the power on it and reprogrammed chip and hey presto...its now working as it should.

regards
kris

 

[Pommie]

Well done. There does seem to be a lot of people experiencing problems with the Vellman kit.

FYI, WPU's are the Weak Pull Up resistors.

Mike.