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[bigdinotech]

I am having problems with the output levels of my EM-406A module.

It used to work fine and I was able to read the output using my microcontroller.

However, it recently stopped working as expected. Further investigation showed that the ouput levels went down to 1V logic levels instead of 2.85V. Since the ouput level is to low I am unable to read it using my microcontroller.

I am able to see the signals using an oscilloscope but at the 1V level.

Thanks,
Dino

[GS_TECH01]

Just a couple of questions about this:

Are you getting any error messages? What are they?
Also, can you provide some info about your microcontroller like specs or datasheet?
What happened before it started to have some issues? Does it not give you the desired output? Please provide more info about this.

The more details you provide, the better for us to understand the problem. Thanks.

[bigdinotech]

I can't tell if I am receiving any error messages since the output level is to low to read using a FTDI chip or a microcontroller.

I am using an ATMEGA328P with the arduino bootloader which works at TTL levels.

I am not sure if the output signal are error messgaes or NMEA messages since I dont have anything to decode the 1V lgoc signals.
It does however seem to output these signals every one second.

[GS_TECH01]

Sorry for the late response. Just wanted to confirm if the ATMEGA328P is this one: (http://www.atmel.com/dyn/products/product_card.asp?part_id=4198). Basically, what does this microcontroller do? Also, is every wire properly connected and hooked up?

[bigdinotech]

Yes that is the microcontroller I am using.

All Im doing is reading the NMEA ouput using the UART.
However 1V logic is to low for this microcontroller.

Everything is wired up correctly.
It just stopped working all of the sudden because my em-406 module switched to 1V logic levels for no apparent reason

Thanks,
Dino

[GS_TECH01]

Got it. Can you check the LED? Is it blinking, steady on, or barely on? Also, can you provide some kind of diagram that shows how do you have the engine module connected to the microcontroller? Like a schematic to illustrate on how you set up/wired everything.

[bigdinotech]

The led is a steady red light.

for the connections it is very simple.
TX of the em406a is connected to the rx of the microcontroller. GND is connected to GND and power to 5V.

[GS_TECH01]

The LED should be blinking if it's able to acquire a fix. Let me go ahead and check with our engineers about this.

[GS_TECH01]

After testing, our engineers suggested not to connect the TX and RX with the MCU. Then, use the oscilloscope to measure if TX is still showing 1V. If so, the EM-406a is possibly broken down. However, if it's displaying 2.85V, that means the setup is wrong between the TX and MCU.

Let us know how it goes.