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26/09/22 - Extender Board Subsystems

A project log for PicoGamePad

A gamepad utilizing the RP2040 Microcontroller. Comes in low-cost and high-performance versions.

miclmicl 09/26/2022 at 02:000 Comments

MAX77751CEFG+ Battery Charge IC. Fairly smart chip, and takes USB lines as an input, simplifying single-cell charging.

Today, I am beginning to finalize the firmware for the V3.0.0-A design, and put together, then cleaned up most of the schematic level design elements for the extension board in the previous log.

Above being the USB interfacing battery charger, and below being the switching regulator with a controlled enable (the bridge to VBUS will change) so that detection of the USB VBUS lines by the RP2040 can indicate to the power system of the extender to switch from discharge to charge/topoff mode.

LMR51420XFDDCR, A really nice recommendation for a switching regular by another colleague.



I've started on some (extremely basic) layout. It's definitely far from something worthy of showing off, but I thought I would add it to the log anyway.

If you read the previous log, you would have seen the first version of the below schematic. It's been quite useful to have, to slowly build up the mappings of interfaces and peripherals in use. I am still thinking about another interesting interface to use, but for now I am fairly sure I will need at least one ADC line for driving the battery charger.


I might add a second log today if I finish the firmware early.

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