Car super-watch
One day it turned out that a watch is needed in the car. The car of the tenth family is equipped with a standard mechanical clock with a very comfortable case. We throw out all the mechanics and sit down at the soldering iron.
The watch is painfully trite, we will create a super watch. Based on the MK ATmega88P-32pin, this is the same 8 Mega only it has two more ADCs. First, let's make our clock on a special DS1307 chip. This microcircuit is a real-time clock with a calendar up to 2100, having a leap year account. Accuracy is ± 1 second per month, provided that the quartz capacity is 2.5pF (From the clock) and the board is properly divorced (you need to walk around the perimeter around the perimeter and put it on the case, for more detailed information see the Data sheet). Another plus is that they do not get off when the power is turned off, because have backup power from a 3V battery. If the voltage disappears, she herself goes into battery mode, one battery lasts for 10 years. With such accuracy, we and the buttons are not needed. But how to set the clock for the first time? Easy. First, in a special firmware, we set today's date and time, but three minutes more. Compile. We are stitching. And at that moment when the set time coincides with the real one - we turn on the power supply of the MC and everything, the time is set. Next, we sew again the MK with normal firmware and use it.
')
After some deliberation, it was decided that a voltmeter and a thermometer were needed. The voltmeter is made on an internal 10 bit ADC with a divider on resistors. The thermometer is made on a digital temperature sensor DS18B20.
A little bit about the design. Everything is done on two boards - the display board and the MK board, arranged in the form of a “sandwich”.
Seven-segment LED indicators. Stabilizer - 7805. Condensers - tantalum. The resistors in the cathode circuit of the indicators are 220 ohms, although you can not put them. Button - date, time / temperature, voltage switch. Ignition input is needed so that the clock shines only during the ignition on and the next 5 minutes after it is turned off. When the clock “goes out” to wake up, just press the button, and they will wake up for another 5 minutes.
Fuse is set to be clocked from the internal oscillator to the frequency of 8 MHz. Two more ADC inputs are left unused, so you can control the voltage at two more points (where fantasy tells you where to measure). The battery is used from the PC motherboard. The thermometer is placed under the bumper or installed after the air filter (next to the DFID). I do not quote the PCB layout, because It was developed for specific indicators that you most likely will not get already (rare).
The front glass has been replaced with a new org. Glass, on which regular tinting has been pasted on the inside. The advantages of this “sticking” are that the entrails are not visible and the numbers are visible in any weather, even when the sun falls right on the clock.
PS Later, consumption per 100km and per hour was added, voltage, engine temperature, speed.
Just set the clock (all the same one button). The time setting algorithm is a bit difficult, but you can figure it out.
Clickable
The watch is painfully trite, we will create a super watch. Based on the MK ATmega88P-32pin, this is the same 8 Mega only it has two more ADCs. First, let's make our clock on a special DS1307 chip. This microcircuit is a real-time clock with a calendar up to 2100, having a leap year account. Accuracy is ± 1 second per month, provided that the quartz capacity is 2.5pF (From the clock) and the board is properly divorced (you need to walk around the perimeter around the perimeter and put it on the case, for more detailed information see the Data sheet). Another plus is that they do not get off when the power is turned off, because have backup power from a 3V battery. If the voltage disappears, she herself goes into battery mode, one battery lasts for 10 years. With such accuracy, we and the buttons are not needed. But how to set the clock for the first time? Easy. First, in a special firmware, we set today's date and time, but three minutes more. Compile. We are stitching. And at that moment when the set time coincides with the real one - we turn on the power supply of the MC and everything, the time is set. Next, we sew again the MK with normal firmware and use it.
')
After some deliberation, it was decided that a voltmeter and a thermometer were needed. The voltmeter is made on an internal 10 bit ADC with a divider on resistors. The thermometer is made on a digital temperature sensor DS18B20.
A little bit about the design. Everything is done on two boards - the display board and the MK board, arranged in the form of a “sandwich”.
Seven-segment LED indicators. Stabilizer - 7805. Condensers - tantalum. The resistors in the cathode circuit of the indicators are 220 ohms, although you can not put them. Button - date, time / temperature, voltage switch. Ignition input is needed so that the clock shines only during the ignition on and the next 5 minutes after it is turned off. When the clock “goes out” to wake up, just press the button, and they will wake up for another 5 minutes.
Fuse is set to be clocked from the internal oscillator to the frequency of 8 MHz. Two more ADC inputs are left unused, so you can control the voltage at two more points (where fantasy tells you where to measure). The battery is used from the PC motherboard. The thermometer is placed under the bumper or installed after the air filter (next to the DFID). I do not quote the PCB layout, because It was developed for specific indicators that you most likely will not get already (rare).
The front glass has been replaced with a new org. Glass, on which regular tinting has been pasted on the inside. The advantages of this “sticking” are that the entrails are not visible and the numbers are visible in any weather, even when the sun falls right on the clock.
PS Later, consumption per 100km and per hour was added, voltage, engine temperature, speed.
Just set the clock (all the same one button). The time setting algorithm is a bit difficult, but you can figure it out.
Clickable
Source: https://habr.com/ru/post/140348/
All Articles