GPS (GP-02) kit module fitted in a GD-77

[F1RMB]

I know about that pin, but there is no PAD for it. What append in case that regulator get shorted for whatever reason, do you thing the MCU GPIO will survive ?

[SQ1TAO]

I know about that pin, but there is no PAD for it. What append in case that regulator get shorted for whatever reason, do you thing the MCU GPIO will survive ?

On EN leg is only pull up resistor and LP3992.
In your scenario fault may can short to ground or pull to 3.3 from regulator gd77. In my case I connect module to 3.3V rail.
In this application (vdd to module from 3.3v rail gd77) this LP3992 is obsolete, but we can use is as power switch.

[oe7abh]

Daniel,

can you make a recommendation as to which modules work best for RT3s?
Which module would you install on the RT3s ?

Thanks, Alfred

[eb4adc]

I know about that pin, but there is no PAD for it. What append in case that regulator get shorted for whatever reason, do you thing the MCU GPIO will survive ?

On EN leg is only pull up resistor and LP3992.
In your scenario fault may can short to ground or pull to 3.3 from regulator gd77. In my case I connect module to 3.3V rail.
In this application (vdd to module from 3.3v rail gd77) this LP3992 is obsolete, but we can use is as power switch.

Hi could you put photos or draw a simple schematic to follow your explanations?
Other question: and ussing N/F pin of gp-02 module? In specs shows that in shutdown mode its consumption is 5ma. Could be affordable?
Thanks in advance.

[SP2AM]

Also added GP-02 module to my GD-77:

- for powering on/off GPS I used voltage regulator that's already on GP-02. In my case it had different markings that LP3992 but was compatible. I lifted pin 3 up (EN), put kapton tape under pin to isolate it from PCB pad and connected pin 3 to pin 97 of mcu (green on download/file.php?id=1938 )

https://docs.ai-thinker.com/_media/gp-0 ... ations.pdf

- pin 99 (yellow) to TX pin on GPS-02 module

- 3.3v and GND from the same regulator as download/file.php?id=1935

- also had to mill case a bit and also mill small slots for antenna cable and the rest of wires

- gps antenna needs to protrude from metal case as much as possible; otherwise I wasn't been able to get any satellite coverage

- obviously forgot to insert battery connector gasket (orange one) when assembling and had to disassembly again

The result isn't great. Can't say it works. It finds 1-3 satellites with low signal, then looses them, find some again etc. That's when testing outside. No satellites found inside. Probably that antena (8x8x4mm) is still not exposed enough or just too small?

[SQ1TAO]

Also added GP-02 module to my GD-77:

- for powering on/off GPS I used voltage regulator that's already on GP-02. In my case it had different markings that LP3992 but was compatible. I lifted pin 3 up (EN), put kapton tape under pin to isolate it from PCB pad and connected pin 3 to pin 97 of mcu (green on download/file.php?id=1938 )

https://docs.ai-thinker.com/_media/gp-0 ... ations.pdf

- pin 99 (yellow) to TX pin on GPS-02 module

- 3.3v and GND from the same regulator as download/file.php?id=1935

- also had to mill case a bit and also mill small slots for antenna cable and the rest of wires

- gps antenna needs to protrude from metal case as much as possible; otherwise I wasn't been able to get any satellite coverage

- obviously forgot to insert battery connector gasket (orange one) when assembling and had to disassembly again

The result isn't great. Can't say it works. It finds 1-3 satellites with low signal, then looses them, find some again etc. That's when testing outside. No satellites found inside. Probably that antena (8x8x4mm) is still not exposed enough or just too small?

In my case I NOT lift 3 leg on LP3992. Maybe your module is loop in on and off again and again... on GP-02 pcb is only pull up resistor connected to this leg. My gd77 still works and CPU without problem drive 3 leg to ground and power out GP-02 without fail.
When in settings GPS is OFF GP-02 is cut off from power supply and I see it in time working on one charge battery.

Outdoor 16sat without problem in that same small antenna. So antenna is not problem in your case.

[SP2AM]

Moved antenna a bit (had to file down its pcb a little), so almost entire ceramic part sticks outside of the metal case. Also soldered back EN pin to pullup resistor. Now it works well (even finds some satellites inside of building).

For EN pin "Maximum input current at EN IEN VEN = 0 V and VIN = 5.2 V - 0.001 µA", so nxp mcu should be able to deal with that without a need for pullup. I think that antenna not sticking out enough was the problem.