Hello everyone. I have a problem with BMP180 pressure sensor and Arduino Pro Mini 3.3V. I'm using SFE_BMP180 library and i noticed, that i have difference in measurements between Pro Mini and Mega2560. Here's the example results:
provided altitude: 220 meters, 722 feet temperature: 24.97 deg C, 76.94 deg F absolute pressure: 985.95 mb, 29.12 inHg relative (sea-level) pressure: 1012.06 mb, 29.89 inHg computed altitude: 220 meters, 722 feet provided altitude: 220 meters, 722 feet temperature: 92.35 deg C, 198.23 deg F absolute pressure: 747.81 mb, 22.09 inHg relative (sea-level) pressure: 767.61 mb, 22.67 inHg computed altitude: 220 meters, 722 feet
Mega's first, Mini's second. What's more, results from BH1750 on both boards are similar, so I think, it's not I2C problem. I've also noticed, that Mega gives results every 5 seconds (delay(5000) on example, so it's correct), but Mini is 2x faster. I have to change also baud rate on Serial Monitor to 19200, because on 9600 I can see only garbage (in code Serial works on 9600). Is it possible, that 3.3V Mini should work with 8MHz? To make it more interesting, it happens, when I select ATmega328(3.3V, 8MHz) board, because on ATmega328(5V, 16MHz) it works fine. Power supply has about 3.3-3.4V.
Probably I don't understand something, so I'd be pleased to show, where I'm thinking in wrong way.