ASCII Characters in sertxd Output ?

#1
I searched the forum on this with no luck..

The following command..
sertxd ("Humidity = ", #HumTotal, cr, lf)

Outputs this..
[00]Humidity = 70 :confused:

I expect this..
Humidity = 70

Does anyone know why the [00] is being written to the output ?

Thank you.
Bud
 

Technical

Technical Support
Staff member
#2
The 00 is not being deliberately written, but may be 'noise' of the electronic circuit in use when the PICAXE chip resets. Try a 10k pull down resistor on sertxd to get rid of the floating reset signals.
 

lbenson

Senior Member
#3
I've also gotten garbage characters with a sertxd right at the beginning of a program. Goes away with a 2 second delay before the sertxd.
 
#4
Technical... I am using an axe091 Dev Board.. So that means the resistor trick can't be done right..

lbenson... Are you saying put a Pause 2000 before the Sertxd caommand ?

Bud
 

Goeytex

Senior Member
#5
Since you did not say, I am guessing from a previous post that you are using a Picaxe 18M2

If you cannot figure out a way to place the suggested resistor, then you might try placing a "Low C.3" as the very first line of the program. This will set the sertxd Pin as an output and make it low. Then use delay of at least 1 second before sertxd is used in the program.

A scope on the sertxd line shows a short positive glitch on the sertxd Pin when the terminal program opens and subsequently opens the com port. The resistor suppresses this glitch.

The diagram below shows how I might place the resistor.

091.png
 
#7
Yes it is an 18M2, I wasn't sure that was relevant. I will try what you suggest below. What is interesting is I have other sertxd lines above these that work fine with no [00] before them. That's what was throwing me off..

Since you did not say, I am guessing from a previous post that you are using a Picaxe 18M2

If you cannot figure out a way to place the suggested resistor, then you might try placing a "Low C.3" as the very first line of the program. This will set the sertxd Pin as an output and make it low. Then use delay of at least 1 second before sertxd is used in the program.

A scope on the sertxd line shows a short positive glitch on the sertxd Pin when the terminal program opens and subsequently opens the com port. The resistor suppresses this glitch.

The diagram below shows how I might place the resistor.

View attachment 18800
 
Top