Hello all!
My first picaxe project is a wood fired boiler controller. The purpose of the controller is to control the air inlet to the boiler, based on the fumes temperature. The goal here is to keep the fumes around 250C, hotter than that and it's wasteful and lower that that it's not burning cleanly.
I measure the fumes with a PT-100 temperature sensor, and I use a geared down stepper motor to control the air inlet hatch. Also in the contoller are 3 buttons, to choose auto / manual mode and 2 buttons to drive the motor manually. 2 leds indicate motor is turning in either direction. So far the controller seems to work, but i seem to have some interference problems, as sometimes the controller behaves a little irregular. Also the required delay for the stepper motor between pulses seems high - there might be some problems with the board layout too, as i've used a veroboard for the design. The slow speed is not an issue, as the boiler response is also rather slow.
For driving the stepper motor I use L6219 IC chip.(actully a whole circuit board stolen from old scanner.. i just cut off the control pins and wired picaxe to those ) The picaxe outputs 0,1,4 and 5 are used to control the current, and outputs 2 and 3 are connected to the "phase" leads. I decided to wire all the current pins individually, in case i would have wanted to use the half and micro-step modes, but they seem to be unnecessary in this case.
Anyways, I've included the circuit schematic, and the picaxe code for axe-18x.. I know the code is rather wasteful, i didn't bother to tidy it up too much as the fits easily in 18x.
ps. I would have included the schematic in gif format, but for some reason the board only accepts very small gif-files.
My first picaxe project is a wood fired boiler controller. The purpose of the controller is to control the air inlet to the boiler, based on the fumes temperature. The goal here is to keep the fumes around 250C, hotter than that and it's wasteful and lower that that it's not burning cleanly.
I measure the fumes with a PT-100 temperature sensor, and I use a geared down stepper motor to control the air inlet hatch. Also in the contoller are 3 buttons, to choose auto / manual mode and 2 buttons to drive the motor manually. 2 leds indicate motor is turning in either direction. So far the controller seems to work, but i seem to have some interference problems, as sometimes the controller behaves a little irregular. Also the required delay for the stepper motor between pulses seems high - there might be some problems with the board layout too, as i've used a veroboard for the design. The slow speed is not an issue, as the boiler response is also rather slow.
For driving the stepper motor I use L6219 IC chip.(actully a whole circuit board stolen from old scanner.. i just cut off the control pins and wired picaxe to those ) The picaxe outputs 0,1,4 and 5 are used to control the current, and outputs 2 and 3 are connected to the "phase" leads. I decided to wire all the current pins individually, in case i would have wanted to use the half and micro-step modes, but they seem to be unnecessary in this case.
Anyways, I've included the circuit schematic, and the picaxe code for axe-18x.. I know the code is rather wasteful, i didn't bother to tidy it up too much as the fits easily in 18x.
ps. I would have included the schematic in gif format, but for some reason the board only accepts very small gif-files.
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