ADH8066 Turns off after connecting

Wireless & IoT
1

I have a ADH8066 GSM module (https://www.sparkfun.com/products/10138) connected to the breakout board (https://www.sparkfun.com/products/10497) and have followed the schematic (http://dlnmh9ip6v2uc.cloudfront.net/dat … Update.pdf). I attached an oscilloscope to the GPIO3 and GPIO10 pins. When I pull the PWON pin low, I can see the GPIO10 pin go high for about 5-10 seconds and then the GPIO3 pin goes high for a split second and then both go low and stay that way.

Picture here: http://sdrv.ms/1e3PY56

At first I figured it was a power issue, so I replaced the power supply with LT1529 voltage regulator (http://cds.linear.com/docs/en/datasheet/1529fb.pdf) which is rated at 3A. I also added a 1000uF capacitor very close to the VBat terminal on the breakout board. Unfortunately, this didn’t help and I’m still seeing the exact same issue. I confirmed with the scope that the lowest voltage seen on the power lines was 3.6 volts, which according to the datasheet is sufficient. I have also connected the voltage regulator to a 350W ATX power supply and still get the same result.

My next thought was that the module was bad. I also have an evaluation board (https://www.sparkfun.com/products/10741) so I plugged the module into that and it worked perfectly meaning that the module is fine. It’s apparently either a faulty breakout board, or I’m messing something up.

What steps should I take to continue troubleshooting this problem?

Thanks,

Matt

2

Hi, I’m having the same problem with my module, I did pretty much the same you did and still can’t figure it out why keeps turning off, do you solve the problem? any suggestion?

Thanks

Dani

3

I have not resolved the problem. I contacted Sparkfun support and they sent me a new board assuming that it was faulty. The new board had the same problem. They suggested that I connect it to a “Breakout Board for FT232RL USB to Serial” (https://www.sparkfun.com/products/718), but I haven’t actually had a chance to try that yet.

I noticed that Sparkfun stopped selling this breakout board, so I wonder if there was something wrong with the design?