I would like to start a shared project to build a solar heater with a PIC controller. Unfortunately I am not a programmer and don't have the time to learn and build the project, so I'm looking for someone to write the program while I build the hardware. I have a good bit of experience building electronic projects and have a home machine shop. I will offer a small award of a low temperature differential Stirling cycle engine that runs on top of a cup of hot water to the person who works this through with me to the end.
I intend to rapidly build this device and make all information available for free on the internet. I will respond rapidly to whoever will help me develop the program. I have the capability to load the program hex file and test it with a QL200 PIC development board. The only programming software I have is gcbasic. I will buy other software if necessary, but I prefer not to.
I don’t want this to be a long term effort where no progress happens for a long time. I’m thinking more of a 2 month development time frame. Following is a basic overview of the project. If you are interested please respond to this post and we can arrange to communicate.
General description
A hot air solar heater consists of a chamber of air heated by sunlight. The first application will be on a residential entry door that faces south. The door is steel and painted a dark color. A storm door with full lexan window is installed between the steel door and the outside. The window is not UV blocking. During periods when sun shines on the door, the air in the space between the steel door and the storm door reaches 150°F. This solar heater will circulate air from the house through the space between the doors to be heated and returned to the house.
A control system using a PIC microcontroller and peripheral devices will control the heater so it only operates when hot air is available. The control system is easily adaptable to other forms of solar hot air heaters. It could also be adaptable to other air heater types other than solar.
Devices
T1 – Temperature sensor DS1820
T2 – Temperature sensor DS1820
Damper 1
DM1 - Damper 1 motor
Damper 2
DM2 - Damper 2 motor
D1S1 – Damper 1 open limit switch (optional)
D1S2 - Damper 1 closed limit switch (optional)
D2S1 - Damper 2 open limit switch (optional)
D2S2 - Damper 2 closed limit switch (optional)
Fan 1
Controller
Basic sequence of operation
T1 measures the indoor air temperature. T2 constantly measures the air temperature between the doors. When the air temperature between the doors is a certain amount higher than the indoor air temperature (high differential), the damper motors drive the dampers to the open position and the fan starts.
If the air temperature differential between the doors falls to below a certain amount (low differential) the fan stops and the dampers close. The high differential and low differential set points provide a dead band to avoid short cycling. Adjustment of the fan speed or damper open limit will also be used to tune the system and avoid short cycling.
Controller
Use of a large PIC microcontroller such as a 16F877A is desirable due to the large amount of functionality and I/O, and general acceptance among the hobby community.
Temperature sensors
The temperature sensors should be serial devices such as DS1820
Damper motors
It would be ideal if the PIC is configured and programmed to control several types of motor so the system builder can select the best type for his design.
A single output could be provided to drive a “smart” damper motor. This would be one that opens when its input is high and closes when its input is low.
A pulse width modulated output can be used to drive a hobby servo to end of stroke positions.
Two outputs could be provided to drive a bidirectional DC motor using an H bridge circuit.
Four outputs could be used to drive a small stepper gear motor like those used in window unit air conditioners to drive the deflection damper. These motors and a small Darlington driver chip board can be bought for $6 on eBay.
In the case of DC or stepper motors, the motors would run until end of travel limit switches are made which stop the motors. If limit switches are used, some input would be required to let the program know they are what stops the motors. A selection jumper for control with limits or without so they will be ignored if the single output of PWM output is used.
Fan
A single output can be used to turn the fan on and off via a relay or other interface.
A PWM output can be used to drive a brushless motor with controller, like those used for RC airplanes. With this type fan motor, the speed could be proportional to the differential temperature. (This is a pretty specialized and not really required for the initial system)
Program
Ideally, to benefit the hobbyist community, the program should be written in a simple and free language like Great Cow Basic. The simplest program would use hard coded set points. It would be very beneficial if the program included the capability to add a LCD readout so the temperatures could be monitored. Going further, it would be great to be able view and change the operating parameters.
Thanks
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I would like to start a shared project to build a solar heater with a PIC controller. Unfortunately I am not a programmer and don't have the time to learn and build the project, so I'm looking for someone to write the program while I build the hardware. I have a good bit of experience building electronic projects and have a home machine shop. I will offer a small award of a low temperature differential Stirling cycle engine that runs on top of a cup of hot water to the person who works this through with me to the end.
I intend to rapidly build this device and make all information available for free on the internet. I will respond rapidly to whoever will help me develop the program. I have the capability to load the program hex file and test it with a QL200 PIC development board. The only programming software I have is gcbasic. I will buy other software if necessary, but I prefer not to.
I don’t want this to be a long term effort where no progress happens for a long time. I’m thinking more of a 2 month development time frame. Following is a basic overview of the project. If you are interested please respond to this post and we can arrange to communicate.
General description
A hot air solar heater consists of a chamber of air heated by sunlight. The first application will be on a residential entry door that faces south. The door is steel and painted a dark color. A storm door with full lexan window is installed between the steel door and the outside. The window is not UV blocking. During periods when sun shines on the door, the air in the space between the steel door and the storm door reaches 150°F. This solar heater will circulate air from the house through the space between the doors to be heated and returned to the house.
A control system using a PIC microcontroller and peripheral devices will control the heater so it only operates when hot air is available. The control system is easily adaptable to other forms of solar hot air heaters. It could also be adaptable to other air heater types other than solar.
Devices
T1 – Temperature sensor DS1820
T2 – Temperature sensor DS1820
Damper 1
DM1 - Damper 1 motor
Damper 2
DM2 - Damper 2 motor
D1S1 – Damper 1 open limit switch (optional)
D1S2 - Damper 1 closed limit switch (optional)
D2S1 - Damper 2 open limit switch (optional)
D2S2 - Damper 2 closed limit switch (optional)
Fan 1
Controller
Basic sequence of operation
T1 measures the indoor air temperature. T2 constantly measures the air temperature between the doors. When the air temperature between the doors is a certain amount higher than the indoor air temperature (high differential), the damper motors drive the dampers to the open position and the fan starts.
If the air temperature differential between the doors falls to below a certain amount (low differential) the fan stops and the dampers close. The high differential and low differential set points provide a dead band to avoid short cycling. Adjustment of the fan speed or damper open limit will also be used to tune the system and avoid short cycling.
Controller
Use of a large PIC microcontroller such as a 16F877A is desirable due to the large amount of functionality and I/O, and general acceptance among the hobby community.
Temperature sensors
The temperature sensors should be serial devices such as DS1820
Damper motors
It would be ideal if the PIC is configured and programmed to control several types of motor so the system builder can select the best type for his design.
A single output could be provided to drive a “smart” damper motor. This would be one that opens when its input is high and closes when its input is low.
A pulse width modulated output can be used to drive a hobby servo to end of stroke positions.
Two outputs could be provided to drive a bidirectional DC motor using an H bridge circuit.
Four outputs could be used to drive a small stepper gear motor like those used in window unit air conditioners to drive the deflection damper. These motors and a small Darlington driver chip board can be bought for $6 on eBay.
In the case of DC or stepper motors, the motors would run until end of travel limit switches are made which stop the motors. If limit switches are used, some input would be required to let the program know they are what stops the motors. A selection jumper for control with limits or without so they will be ignored if the single output of PWM output is used.
Fan
A single output can be used to turn the fan on and off via a relay or other interface.
A PWM output can be used to drive a brushless motor with controller, like those used for RC airplanes. With this type fan motor, the speed could be proportional to the differential temperature. (This is a pretty specialized and not really required for the initial system)
Program
Ideally, to benefit the hobbyist community, the program should be written in a simple and free language like Great Cow Basic. The simplest program would use hard coded set points. It would be very beneficial if the program included the capability to add a LCD readout so the temperatures could be monitored. Going further, it would be great to be able view and change the operating parameters.
Thanks
Contact me off-forum to discuss this: joe at teremo.com
Joe