Help with homemade arduboy schematic

S1 should be connected to B- instead of ground and D1 and D2 shouldn’t be connected because they’re already connected together in the IC?

No, it doesn’t hurt to connect D1 and D2 externally. It’s actually better to connect them to lower the resistance between D1 and D2.

Follow the DW01 datasheet for the rest.

I think I’ve fixed everything now, I’ve also increased the fuse rating to 1.25A since the tp4056 will charge the battery at 1A

The protection and charge circuits look OK now.

I don’t know what OUT_B+ is on pins 2 and 3 of the power switch. I think it should be VBAT_CHARGE/B+/P+

Pin 1 on the power switch should go directly to regulator U1 VIN pin 3, not UVCC.

I would use a 6 pin ICSP PROGRAMMER_HEADER instead of a 10 pin, to save space, unless your programmer has a 10 pin header and you don’t want to rewire it or use a converter. If you stay with the 10 pin, your pinout doesn’t match the standard (You have it rotated 180 degrees).

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Ah yes it should be P+, I forgot to change the net

And then UVCC should be connected to the LDO U1 OUT pin,before the decoupling caps, right? Or to the fuse after USB1 pin 1?

Yes I have this 10 pin USBasp programmer, I’ve fixed it now

No, it should remain as you have it now. UVCC should be F1 output, U4 VCC/CE, U2 UVcc/VBus.

I have a similar one. You can get 10 pin to 6 pin adapters.

Note that I found that the programmer I have wasn’t fully 3.3V compatible. Yours is different than mine, so I don’t know if it has the same problem.

No you haven’t. GND should be on pins 4, 6, 8, 10 not 1, 3, 5, 7

I moved the index pin too, the black tab on the top of the connector, isn’t it right?

The position of the index tab is correct with relation to the signal names. The pin numbers are wrong. Look at the silk screen of the programmer in the photo you linked to. Pin 1 is MOSI and Pin 9 is MISO.

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Ok I fixed that, thanks. The design manager kept giving me a warning about multiple nets in the same wire, so I merged the nets B+, VBAT_CHARGE and P+ into B+. And I’ve deleted P- because it just connected to ground. Have I messed something up?

I don’t see any more problems (but again, I haven’t checked that all the ATmega I/O pins are wired to the correct parts).

Many of the names (xxx_PAD) you’ve given to your test pins don’t match what they’re connected to (and you don’t have a T7).


I’ve followed the pin table (Arduboy
Leonardo/Micro column) you linked me in your first reply and MrBlinky’s thread about the flash cart so everything should be ok

Damn all these dumb mistakes… fixed them
Now I can finally get my hands dirty and lay out the pcb :smile:

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You might be better to name the PF0 and PF1 test pins after their Arduino pin names.
PF0 = A5
PF1 = A4

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You have the flash memory chip wired according to the “old” design, where CS is wired to PD2 (RX). You should probably follow the “new” design, where CS is wired to PD1 (SDA).

But in the post there’s a note saying “Use new wiring only when hardware serial will be used for special tasks” and personally I think I will never use the Serial Communication, maybe it’s more likely that I’ll use the SDA and SCL for I2C communication, I’ve also got some sensors that use I2C.
I was thinking about using a resettable fuse instead of the normal one, can the leakage current damage the circuit? What do you suggest me?

OK, but the upcoming official FX mod will use the “new” wiring, so it will likely take less effort to use it. Then again, maybe the “old” wiring is easy, as well. Maybe @Mr.Blinky can weigh in on this?

You could probably still use I2C with the “new” wiring, as long as you didn’t write to or read from the flash chip or display while using the I2C bus.

I assumed you were going to use a resettable polyfuse.

What leakage current?

Leakage current of the resettable fuse

There’s nowhere for current to “leak” from a resettable fuse. A polyfuse may have a bit more resistance when operating than a normal one, but that shouldn’t be a problem.

Here it says that PTC fuses have some leakage current during the “tripped” status. Maybe I’m just confused and and a PTC and a resettable fuse/polyfuse are two different things?

The fuse is to protect from burning up traces or damaging components on you circuit board, due to high current or a short caused by a wire or some other device. If the high current is due to something other than a dead short, that component is likely already damaged. The small amount of leakage current that can flow though a tripped polyfuse will be so low that it won’t be able to cause any further damage.

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Oh ok, thanks for the explanation