Vermes
Advanced Member level 4
It is a project of car computer on Atmega8.
Functions:
Temperature measurement is done by 1wire sensors DS18B20.
Voltage measurement is done by a divider which increases the range of the meter to 15V.
The device checks if the lights are on by opto-coupler connected to the backlight of the rear window heating button.
To detect the enabling of the ignition, you can connect by the opto-coupler to the cable in the radio, on which the voltage appears after turning the ignition.
In order to indicate alarm on/off, you can use interrput input INT0 by 2 diodes, to which the central locking signal (close/open) is connected. It is controlled by the ground.
How it works:
The device works all the time, the welcome appears after turning the ignition. Then the device checks the voltage – if it is greater than 13,5V, it means that the engine is on and the device checks if lights are on. If they are not, you are informed to turn on lights, which is indicated by buzzer. After turning on lights, program continues to work.
Then the level of fuel, voltage and temperature measurements are performed.
Measurement of the level of fuel in the tank with use of original sensor of level of fuel may cause some problems. The measurement can be very unstable because of the waving of fuel in tank. So you need a way to stabilize and delay the read. RC filter was used to do that, and because the car measures the level of fuel using AC voltage, you have to add a diode. From the software, the solution is to apply average of the measurement. The measurement is performed for 1 minute, every 7 minutes and then divided into 7 and calculated into liters.
Measurement of fuel burned in assumption should look like that:
When you start a trip, reset the meter of fuel burned and drive. After the end of the trip you know, how much fuel was burned.
To measure the amount of fuel burned, you use the measurement of injection time * injection constant.
By the matching system, the injection is connected to the INT1. The time of occurence of low state at the input of the system matching, which theoretically corresponds to the opening of the injection is measured by using timer1.
Scheme of the matching system:
Scheme of the computer:
U4 are Schmitt gates.
Link to original thread (useful attachment) – Komputer samochodowy do VW GOLF IV
Functions:
- inside and outside temperature measurement
- voltage measurement in car installation
- measurement of the fuel level in tank
- measurement of the amount of fuel burned
- warning about the lights that are not on when the engine started
- flashing signal of enabled alarm (instead of alarm diode)
Temperature measurement is done by 1wire sensors DS18B20.
Voltage measurement is done by a divider which increases the range of the meter to 15V.
The device checks if the lights are on by opto-coupler connected to the backlight of the rear window heating button.
To detect the enabling of the ignition, you can connect by the opto-coupler to the cable in the radio, on which the voltage appears after turning the ignition.
In order to indicate alarm on/off, you can use interrput input INT0 by 2 diodes, to which the central locking signal (close/open) is connected. It is controlled by the ground.
How it works:
The device works all the time, the welcome appears after turning the ignition. Then the device checks the voltage – if it is greater than 13,5V, it means that the engine is on and the device checks if lights are on. If they are not, you are informed to turn on lights, which is indicated by buzzer. After turning on lights, program continues to work.
Then the level of fuel, voltage and temperature measurements are performed.
Measurement of the level of fuel in the tank with use of original sensor of level of fuel may cause some problems. The measurement can be very unstable because of the waving of fuel in tank. So you need a way to stabilize and delay the read. RC filter was used to do that, and because the car measures the level of fuel using AC voltage, you have to add a diode. From the software, the solution is to apply average of the measurement. The measurement is performed for 1 minute, every 7 minutes and then divided into 7 and calculated into liters.
Measurement of fuel burned in assumption should look like that:
When you start a trip, reset the meter of fuel burned and drive. After the end of the trip you know, how much fuel was burned.
To measure the amount of fuel burned, you use the measurement of injection time * injection constant.
By the matching system, the injection is connected to the INT1. The time of occurence of low state at the input of the system matching, which theoretically corresponds to the opening of the injection is measured by using timer1.
Scheme of the matching system:
Scheme of the computer:
U4 are Schmitt gates.
Link to original thread (useful attachment) – Komputer samochodowy do VW GOLF IV