I have a small device that uses MT7620N:
https://www.anz.ru/files/mediatek/MT7620_Datasheet.pdf
I want to add a USB functionality, so I'm focused on UPHY0_VRES, UPHY0_PADM, UPHY0_V33A, UPHY0_PADP and UPHY0_V12D.
The UPHY0_PADM and UPHY0_PADP are supposed to be the -data and +data for USB. Seeing that the pins at visual inspection don't lead anywhere, I'd say the the rest of the device don't use it.
The UPHY0_V33A and UPHY0_V12D I think are taken cared of as the supply is 3.3V and the UPHY0_V12D pin seems to go through a via that then leads to a LD5NG or LD5N6. I can't make out the etching that clearly and my searches turn up nothing. But it looks like those 5 pin linear regulators, so I'm betting it's a 1.2V step down regulator.
The UPHY0_VRES from visual inspection looks like it's left floating, or it went through a via underneath the CPU (it is in an inner pin). I don't have any idea how this should be used, but the datasheet says the resistor needs to be 8.2kohm in value. It doesn't say if it's a pull up or a pull down. I don't have a clue as to how to attach a resistor here, if one is really needed.
I haven't probed everything yet, as all the traces are tiny and in some cases I think I'd rather scratch off the solder mask. So I'll have to finish up those needle probes that I left unfinished somewhere here in my room.
https://www.anz.ru/files/mediatek/MT7620_Datasheet.pdf
I want to add a USB functionality, so I'm focused on UPHY0_VRES, UPHY0_PADM, UPHY0_V33A, UPHY0_PADP and UPHY0_V12D.
The UPHY0_PADM and UPHY0_PADP are supposed to be the -data and +data for USB. Seeing that the pins at visual inspection don't lead anywhere, I'd say the the rest of the device don't use it.
The UPHY0_V33A and UPHY0_V12D I think are taken cared of as the supply is 3.3V and the UPHY0_V12D pin seems to go through a via that then leads to a LD5NG or LD5N6. I can't make out the etching that clearly and my searches turn up nothing. But it looks like those 5 pin linear regulators, so I'm betting it's a 1.2V step down regulator.
The UPHY0_VRES from visual inspection looks like it's left floating, or it went through a via underneath the CPU (it is in an inner pin). I don't have any idea how this should be used, but the datasheet says the resistor needs to be 8.2kohm in value. It doesn't say if it's a pull up or a pull down. I don't have a clue as to how to attach a resistor here, if one is really needed.
I haven't probed everything yet, as all the traces are tiny and in some cases I think I'd rather scratch off the solder mask. So I'll have to finish up those needle probes that I left unfinished somewhere here in my room.
