error port already open, 8005

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error port already open, 8005

Post by Guest » Wed Jul 28, 2004 10:23 am

hi, when I try and use screamer to program 16f88 that I've burned bloader to, I get the following error

"error port already open"

and then


a couple questions >

1) does it matter which pins the rx and tx are connected to? I have rx on pin 8 and tx on pin 11

2) once I've loaded the bloader onto the pic, should it be outputting anything? I can see a square wave on some of the pins if I look on my scope but not on all of them. I didn't get anything coming back using hyperterminal. What baud rate should hyperterminal be looking for?

3) I'm pulling mclr high. when do I pull it low to download more code?

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Post by pittuck » Wed Jul 28, 2004 11:26 am

The error is due to some other software using the port. Do you have a PDA by any chance?

1) Check the 16F88 datasheet.

It says RX pin is 8 this should be connected to the PC's TX pin, the TX pin is 11 this should be connected to the PC's RX pin.

2) The pic should send out a letter on boot, 9600, 8 bits, 1 stop, no parity (Spell?) and NO flow control.

3) Yes, u pulling high using a 4k7 resistor or somming? To program u should pull MCLR to ground, i use a mini push button conected straight to GND.


Post by Guest » Wed Jul 28, 2004 2:56 pm

so, it should be transmitting a serial signal on pin 11? I'm not getting anything on pin 11 when I look my scope, however pins 17-19 are going from high to low at varying frequencies.


Post by Guest » Wed Jul 28, 2004 3:10 pm

oops, I mis-measured. pin 17 is outputting a square wave, which I guess makes sense since it's the clock out.

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Post by sparky » Fri Jul 30, 2004 8:51 am

Sounds like you've got another program using your port such as hyperterminal. Make sure you've got all other programs closed that may use the serial port.

I'm a little confused .. Where are you getting Pin 11 on a DB9, 9 Pin connector? Oh wait, you mean the PIC pins. I follow. RX is Pin 8 and should be connected to the TX of your RS232 circuit. TX is Pin 11 on the PIC and should be connected to the RX of your RS232 or equivalent circuit.

Bloader initiates a download during Power On Reset. This means that bloader will check to see if there is something new to download every time th PIC is powered on (Vdd goes to 5V) or whenever the PIC is reset (by pulling MCLR to 0V and then releasing it back to 5V by using a momentary push button). You should use a push button switch to reset the PIC.

If you just burned Bloader-xxx.hex onto a chip, you should see 'Ok' repeating every second or so in hyperterminal. It's all explained in the readme.txt file included with the zip file. 'Ok' is sent out at 9600 bps. Of course, once you load something new onto the chip, this little 'Ok' program will be over-written.


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Post by pittuck » Fri Jul 30, 2004 10:05 am

Again, do you have a PDA. With the palm software set to a serial port i get this error. I dont know why it was set to a serial port cause my PDA Dock is USB, but thats totally different can of beans.

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Post by Nathaniel » Mon Jun 22, 2009 4:30 am

i agree...port might be in use of some other program, that's why you are getting the error message.

and pattuck why are you asking about PDA?
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Post by FartingMonkey92 » Mon Jun 22, 2009 8:34 am

Wow, epic bump. :wink:

Anyway, it was most likely some other program/device using the same port with a VCP driver.

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