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I'm considering upgrading my dad's old tablet, which currently has a micro USB connector. The issue arises from his habit of frequently misplacing the charger, and I'd prefer not to rely on an external adapter.

My plan is to retrofit a USB-C connector, making it more versatile and allowing for charging using a standard phone charger. Naturally, I aim to connect both the D+ and D- pins for battery testing, as well as the CC pins. Given that the tablet lacks full USB power delivery support, my requirements are limited to power provider and power source functionalities.

After conducting some research, my proposed solution involves adding lines from the CC pins to resistors Rp and Rd. Being relatively new to electronics, I'm curious: is this approach feasible? To my understanding, omitting connection to the TXp, TXn, RXp, RXn, dp, and dn lines of USB 2.0 and 3.0 should not cause any issues. I welcome opinions, suggestions, and validation of my approach. Thank you in advance.

PS: Apologies for any grammatical or stylistic errors; I'm still learning English.

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    \$\begingroup\$ I don't uneerstand why you need D- and D+ for battery testing. What do you think those wires are used for? \$\endgroup\$
    – Justme
    Commented Apr 27 at 7:44
  • \$\begingroup\$ @Justme Thanks for answering! Excuse me for the delay to answer you. then, you could connect the 2 differential ground pairs to some ground plane of the PCB. I understand that I made a mistake in the previous question regarding the lines dn and dp. \$\endgroup\$
    – condor12
    Commented May 2 at 18:25
  • \$\begingroup\$ What do you mean by "2 differential ground pairs"? USB does not have 2 differential ground pairs. \$\endgroup\$
    – Justme
    Commented May 2 at 18:41

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Yes, assuming a product is only a USB Device, replacing a MicroUSB receptacle with Type-C receptacle is as simple as replacibg the connector, adding two resistors and wiring it correctly. However tablets generally are USB OTG devices that can take the role of both Device and Host as needed.

But it seems there is some misundestanding, D- and D+ are DN and DP. They are also high speed USB data wires, communicatig at 480 Mbps, and requires them to be wired as differential pair with matched transmission line. If you are not familiar with how to wire high speed differential buses you may run into trouble if connecting it to a PC for data transfer does not work any more.

Also any phone charger can already be used for charging the tablet, if you buy a cable or an adapter with suitable connectors on both ends. These cables are not obsolete yet.

One final problem is that the MicroUSB has an ID pin which is used to determine the role of the USB connection. Most tablets can be "Devices" when connected to a charger or PC, and can switch to a "Host" role when connecting to other "Devices" such as USB sticks or sound interfaces or whatever.

As the mechanisms for determining the role of the device is completely different in Type-C, you would need to design the port role detection circuit of Type-C and convert it to the ID signal for original MicroUSB interface.

The cables and adapters you can already buy have this so you don't have to design in, program, and use a Type-C port cobtroller IC for this feature.

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  • \$\begingroup\$ @condor12 There might be no simple and standalone solution. The tablet was made for MicroUSB. Retrofitting an old tablet with Type-C may not be worth it, compared to buying suitable MicroUSB cables, which is far simpler. \$\endgroup\$
    – Justme
    Commented May 2 at 18:38
  • \$\begingroup\$ I could connect the 2 differential ground pairs to some ground plane of the PCB. I understand that I made a mistake in the previous question regarding the lines dn and dp. What do you recommend I do with high-speed data cables? I don't really care much about data transfer speed. Now my question is how to design the function detection circuit of the type C port and convert it to the identification signal for the original MicroUSB interface, is it possible to do this without needing an ic? \$\endgroup\$
    – condor12
    Commented May 2 at 18:40
  • \$\begingroup\$ I would appreciate if you have any source or information that could be useful to me. I have been investigating and I understand that a USB Type-C Controller would solve this, the problem is that I live in Argentina and many ICs that could be useful to me are not available here in my country. I have only been able to find the TPS65994AE ic and possibly I can get the STUSB1600 or something similar here, which would be ideal, although I am not entirely sure that they will serve my purpose \$\endgroup\$
    – condor12
    Commented May 2 at 18:40
  • \$\begingroup\$ Thank you. Yes, I know. It just has great sentimental value for him and he wanted to try it. Sorry, earlier I meant ground plane, not differential pair hehe \$\endgroup\$
    – condor12
    Commented May 2 at 19:54

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