Serial comms / Bootloader

[mister_e]

Probe your MCLR pin when you disconnect the RS232 cable.

What's happen? Should go to GND for XYZ time. Place a pull-down resistor on pin 8 of your MAX232.

[koossa]

Hi Steve

Thx
I don't have instrumentation to do a probe on mclr.
Must I just put a pull down resistor on the max (What size 2k)?

[mister_e]

let's say <10K should be enough. Also... be sure MCLR is tie to VCC with pull-up too.

[mister_e]

a simple probe... use another PIC.

Start:
    While PICInput=1 : wend
    HIGH LED
    pause 2000
    LOW LED
    goto Start

[koossa]

Thank you!

[koossa]

Hi Steve

Someone told me that the MAX232 has an internal 5K pull down.
It would not be necessary to put a pull down resistor as you have described.

Is this correct?

[mister_e]

If i refer to the Maxim datasheet...
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=573&stc=1&d=1130593189 ">

there's indeed a pull-down resistor... mmm for the TI one, i guess it's the same.

mmm... Hyperterminal could be the cause...

1. did you disable the handshaking?
2. What about if you use MicroCode Studio Serial Communicator instead?
3. Is your MCLR pin is tied to VCC via resistor?
4. What about if you use the original solution (resistor instead of capacitor)?

I bet on the Handshake idea now.