PIcaxe 18 connected to laptop

[doggington]

Firstly many thanks for the replies to my previous questions.

I am experimenting with the picaxe18x with an infrared reciever and a stepper motor for no other reason than curiosity. A short little program runs the stepper forewards and reverse through the Darlington 2803. The motor is running on 12v. The picaxe is running on a regulated 5v supply from the 12v battery. If I add an infrared reciever with ''if pin0 = 0 then.....'' etc the program runs fine as long as it is still connected to my laptop via the download cable. when disconnected the stepper part of the program runs continuously and the infrared is ignored. Conversely running a stepper program on another picaxe board with the L293d driver and similar power supplies the program only runs properly if the laptop is disconnected!!!
best wishes

pete

 

[inglewoodpete]

Instability of a PICAXE after you disconnect the PC suggests that the download circuit is not wired correctly on the PICAXE baord. With the power supply and download cable disconnected, remove the PICAXE chip from the board. With a multimeter, check the resistance between the serial in (download) pin of the PICAXE chip socket and 0v on the board. The reading should be around 32k ohms (22k + 10k). I suspect that your board's download circuit is open circuit. The 32k to 0v holds the input low when the PC is disconnected.