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Hello. I'm trying to connect the module HM55B (electronic compass) with MCB 2378. The module operates at 5 volts and I want to connect FAST GPIO pins that go to 3.3 volts. How I can do? Thank you very much
Sorry , it´s mcb2378
LPC2378 have 5V-tolerant pins, so if signals are only sent to the processor, then it's enough if you add a series resistor for each signal.
If signals goes from processor to sensor then you need to check if the sensor can accept +3.3V as logic high with enough safety margin. If not, then you may have to use a pull-up to 5V and send data by changing the I/O pin between input (pulled to 5V) and output driven low. Or buy a level-changer chip and place between. Or put a transistor between.
Standard electronics stuff. You have spent time reading the datasheet/user manual? And you have read up a bit about mixed-voltage interfacing?
Yes. I have the chip in my hands and I've used it with arduino. I have read the three sheets that I found on the internet and says the same (5 v). I had thought of two ideas. 1st to send the data to the sensor using a transistor working in court and saturation (BC 547). 2 º To receive data from the sensor to LPC2378 using a voltage divider. Thank you for your help Antonio Moyano
In the data sheet at the beginning says "The sensing device on the Compass Module is a Hitachi HM55B chip. An onboard regulator and resistor protection make the 3 volt HM55B chip compatible with 5 volt supply BASIC Stamp ® microcontroller and signal levels". I do not know if it will work when connected to 3.3 volt Vcc, since then he says that the Vcc is 5 v. It has a voltage regulator. If I want to receive data from the sensor, which is the amount of resistance I have to put in series. Please, Do not get angry with me. Antio Moyano
"says the same (5 v)."
The ones I found clearly said that the chip itself was 3V3 - the module is supplied with 5V, but has an onboard regulator that drops this to 3V3.
Maybe you have a slightly different variant of "HM55B (compass sensor)" - so you need to provide links to the actual documents that apply to the actual version of the actual part that you're actually using.