Pickaxe 28*1 starter pack

S

sreedev

Member
Hi,
I have a picaxe 28*1 starter pack. I did not program the PICAXE which came with it. I soldered a male header pin to output 0 on the board(Port), connected a servo to it and the servo is rotating. I know that there is a bootstrap in the microcontroller. Does the working of the servo mean that there is an addtional program burnt onto the mc by the factory(PICAXE).
 
Technical

Technical

Technical Support
Staff member
There is no pre-programmed program to move a servo on output 0. This, combined with your other thread about not being able to download, implies there is a soldering issue (check the header you added) or power supply issue with your board.
 
W

westaust55

Moderator
nick12ab said:
According to PICAXE Manual 3, a servo receiving no pulses will move freely to any position. Maybe this is what you are seeing.
Click to expand...
I believe that the "move freely to any position" means that when there is no signal, the ServoMotor is not under control to hold a position (in effect electrically disengaged) and thus the output shaft is free to be turned by hand to any position.
Note that turning a servo output by hand may cause damage such as stripping gears in the case of nylon gears or breaking parts if the end stops are encountered and too much force is applied.
 
W

westaust55

Moderator
There is no program supplied in a new PICAXE specific to control of a ServoMotor.

New PICAXE chips do come with a pregrammed code to output a message on the SerialOut pin (pin B.0 on some M2 chips) with a message along the lines of "Hello I am your PICAXE".
I surmise that this "welcome" message could be seen as pulses by a ServoMotor and some of the pulses may, by perchance, be of durations in the correct range to be interpreted by the ServoMotor as commands to move to specific positions.

Also, when a PICAXE is programmed, as the program is downloaded from the PC to the PICAXE chip, data is sent from the PICAXE to the PC via the SerialOut pin for the purposes of program verification.

With PICAXE chips that share the SerialOut pin with other IO fucntions, if the operation of the SerialOut pin during programming might result in a damaging situation (such as operation of a motor) then it is best to incorporate a jumper link or switch to disconenct the driven device during programming of the PICAXE. Some of the Rev Ed development/proto boards for the M/M2 parts include such a header and jumper (eg AXE021).
 
You must log in or register to reply here.
Top