Summary of Mini Digital Barometric Altimeter
This article describes a miniaturized digital barometric altimeter designed for model rockets, featuring a compact 36x12 mm PCB. The device integrates a 12V battery holder and an altimeter sensor, achieving a total height of 18 mm and a weight of just 13 grams with the battery. Key features include high-resolution altitude recording via EEPROM, USB data download, and acceleration-resistant design to prevent contact failure during flight.
Parts used in the Mini Digital Barometric Altimeter:
- 12v 23A battery holders
- Small Digital Barometric Altimeter
- Microcontroller Unit (MCU)
- 128Kb EEPROM memory
- USB connector
- PCB (36×12 mm)
- ICSP programming interface
- Insulation tape
I found on Ebay very nice, small 12v 23A battery holders for PCB mounting style and decided to fit the SMALL DIGITAL BAROMETRIC ALTIMETER just on the back of the holder.
So basically this is the same schematic as the SMALL DIGITAL BAROMETRIC ALTIMETER, however I moved some of the connections to different MCU pins because of PCB space limitations.
In spite of the small size the functional remains the same.
– 128Kb EEPROM memory which allows approximately 3.5 minutes of recording
– 40 record per second
– Blink integer values up to 9999 meters
– USB connector for memory download
– 13 bit ADC resolution trough oversampling
– 1m per bit resolution
– On the field it will calculate and show maximum altitude
– Temperature adjusted for 20 degrees Celsius
– ICSP programming capability
– Auto start detection
After that the PCB was a bit of a challenge with those small dimensions but I managed to fit everything on a 36×12 mm PCB.
Once I soldered all components the height was 5 mm.
And after I mounted the battery holder the total height is 18 mm to give the final dimensions of 36x12x18 mm.
Of course the weight is as important as the size and normally both are related so the final weight was also reduced to 4gr without battery and 13 grams with the battery.
Because this mini altimeter is intended for model/experimental rockets and thus high acceleration forces there were some concerns about how stable the battery will be held in the holder and whether the acceleration will not open the contacts and restart the device.
So taking into consideration the weight of the battery and the usual accelerations in the hobby rocketry I’ve calculated the force that the battery will apply on the metal spring. I’ve also measured the force necessary to bend the spring and there is considerable safety margin.
The only potential problem I see is that if the battery is subject somehow to horizontal acceleration it can be somehow ejected from the holder because of the spanned spring. This is of course easily fixable with a piece of insulation tape.
Read more: Mini Digital Barometric Altimeter
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What are the final dimensions of the assembled device?
The final dimensions are 36x12x18 mm after mounting the battery holder. -
How much does the device weigh with the battery?
The final weight is 13 grams with the battery included. -
Can this device record data at a high frequency?
Yes, it records at 40 records per second using 128Kb EEPROM memory. -
How is the battery secured against high acceleration forces?
The spring force was calculated and measured to ensure a considerable safety margin against opening contacts. -
What happens if the battery is subjected to horizontal acceleration?
The battery might be ejected from the holder due to the spanned spring. -
How can the risk of battery ejection be fixed?
It can be easily fixed by applying a piece of insulation tape. -
Does the device calculate maximum altitude automatically?
Yes, it calculates and shows the maximum altitude while on the field. -
Is ICSP programming capability available on this board?
Yes, the device includes ICSP programming capability.
