Hi, I just purchased the Servo2040 board, and I’ve been looking for a pinout reference sheet to explain the pins on the opposite side of the servo headers. In particular what are A0, A1, and A2. Are these 3 analog inputs in addition to the 6 next to the LEDs? What is SWC and SWD?
Also, why didn’t these pins come with headers soldered?
Thanks.
There is a link to the schematic on its shop page.
Poke around there and you should be able to sort it out. ;)
servo2040.sch (shopify.com)
SWC and SWD are I believe the Serial Wire Debug pins.
A0, A1 and A2 are the ADC 0 , ADC 1 and ADC 2.
One more question…It was mentioned to use higher servo voltage, you need to break the trace on the back. So…
OK, if your external supply is 5V, you don’t need to cut the jumper.
That external 5V will power everything, if you don’t cut the jumper.
It will also try to back power through the USB port.
You will need a Data only USB cable.
I ran into a similar issue on my Interstate 75. The Pico Power Supply wasn’t enough, current wise to drive my 64 x 64 LED matrix. I needed an external supply and wanted it to run the works. I have a USB cable that I cut the +5V wire on. I program it with that custom cable.
If your external supply is higher than +5V you need to cut the jumper to prevent damage to the RP2040 etc.
If you cut the jumper the external supply only powers the servo’s.
You will need to power the Servo 2040 via the USB port.
No need for a custom USB cable, for programing.
Hope that helps.
That helps alot to understand it. So, if I use an external 7.4v lipo, and I cut the jumper, the servos will be powered but nothing will happen because the Servo2040 board will not be powered?
I guess for a wireless solution, you will need a buck converter to step the voltage down to 5v, then feed this into the USB-C?
Too question 1, yes.
Too question 2, yes, that will work. The Servo 2040, by itself won’t draw much current.
If you plug an official USB C (Pi 4) Power supply in to the USB port on the Servo 2040, no need for a buck converter. Just FYI.
For question 2: that would mean you will have to have 2 power supplies.
1 more question. the 5V and - connections right below the QW/ST connector…are they inputs or outputs?
Yes, you would have two power supplies.
If you go with 5V servo’s and you can use one supply.
Those 5V and + and - are normally outputs. The + is VBUS and the - is ground.
In this video https://youtu.be/OQ4Wjgn8A78?t=321 you can cut the trace and power the terminals with 5v. So, looking at the back of the Servo2040, which one is 5V and which is ground?
The jumper / track you cut is over where it says Separate USB and external power. The shiny bit that looks like a dumb bell.
But according to this video https://youtu.be/OQ4Wjgn8A78?t=321 after you cut the trace, you can power the terminals with 5v instead of using the USB-C port…
I was wondering which terminal is which. So, looking at the back of the Servo2040, which one is 5V and which is ground?
The “screw terminals” ? It’s marked on top for those.
The + is the 5V
The - is ground.
I mean the part that you break on the back. It will leave 2 seperate traces when you break it. According to the video you can power that with 5V,.or am I misinterpreting what he said?
Ok, I’m going to rehash this a bit. You have IMHO misunderstood some of that video.
As is without the trace cut, the Servos and the Servo2040 both get +5V from the USB jack. If you only have a couple of servos connected this should be fine.
Or alternately, you can feed in +5V via the screw terminals and power both the Servo 2040 and the Servos. You do this if you need more current than the UBC jack can supply. You don’t need to cut the trace if your using a 5V power supply. It will back feed through the USB jack though. A Data only USB cable should be used.
If you do decide to cut the trace, you need to do the following.
Power the Servo2040 via the USB Jack.
And power the Servos via the Terminal Block.
A normal USB cable is used for programing and power to the Servo2040.
Ok, I got it. So, with the trace uncut, you can only supply 5V max to the terminal screws? If you supply more than 5V to the terminal screws, you will need to cut the trace?
Yes, that is correct.
Appreciate the help alphanumeric, but I have just 1 more question. When you cut the trace and are using 7.4v or 11.1V on the terminal, and you have programmed the robot and want it to be free from the computer, is there another way to power the board other than the USB-C port? Is there a way to power it via the headers somehow?
There are solder pads for 5V and Ground down by the Qwicc connector.
So, does it matter if you power the board using 5V or 3.3V?
That I don’t know.
As far as the Pico goes if your powering it via VSYS, 3.3v is fine.
You’d have to check the schematic to see what the 5v feeds other than the servos.