I tried hard not to make this post, but I am out of ideas.
I built a custom board for the g120 and no matter what I try. I cannot get them to boot (detected as a USB device)
I followed the reference design and believe to have all required connections. However at the bare minimum, I would expect that 3.3v, GND, reset pin pulled high and of course the USB d- and and USB D+ (to client USB) should be all that is required for the computer to recognize the module.
The unit has power. I am read 3.3v output voltage on most of all the pins, except the USB pins and a few others. However, thats as far as it goes.
Has anyone else been able to get their modules working (NOT HDR)?
You only need to check: 3.3V, GND, reset, LDR0, LDR1 and MOD which I believe they are marked in red in brochure. Maybe VBAT is causing problem so connect to 3.3V?
Regarding the MOD pin. Do you need some kind of signal feed to it? I thought just leaving it floating would result in USB debugging mode? The only connection I saw to the mod pin on the reference design was to a header pin.
My guess looking at the G120 brochure is that the MOD pin needs to be pulled high for USB or to GND for COM1. I don’t think it should be left floating.
Well I think I have done everything I can think of. There is only but so much documentation ( connect this, connect that end of story). I have gone over it 20 times. Its pretty straight forward.
I have spent over 12 hours on trying to get these modules working.
Either something is missing from the reference design, the modules don’t have the firmware/bootloader, or my modules are DOA.
@ BrightIdea - Are you talking about device manager or TerraTerm?
Mine didnt show in device manager at all but in TerrraTerm there was a com port and away we went…
One thing I have found, which may be meaningless is that Pin 67 (Client D-) is being held low. If I put 3.3v to it., the computer recognizes the connection of a USB device, but says it is unrecognized.
@ BrightIdea - Did you try pulling LDR0 and LDR1 low and then powering it up to see if it enters the 'GHI Bootloader" mode?
Edit,
Pulling D+ and D- up or down, depending on the combination, tells the Host controller if a device is attached and what speed to run at. Sounds like your tricking your PC into thinking somethings attached when it is not / not responding.