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Black is ground. Red is VCC, White is signal (i/o). (note, that photo is of a prototype board where the signal pins are blue, and there is an extra set of signal pins along the left side header row that do not exist on the production EZ-B's).



Red vcc, black ground white is signal. Blue is replaced with white.


I am trying to get the HC-SR04 to work, but having issues. I did 3d print some parts and it looks great.

Here is what I have tried: HC-SR04. Digital pins Gnd----------------D20, black pin ECHO--------------D20, white pin TRIG ---------------D21, white pin VCC ----------------D21, red pin

Set up in ping distance control.

Not getting anything but 255 from sensor. Tried second sensor and got the same thing. Will the 7.4 volts work with the VCC on the ping sensor?

I've successfully done this on the v3 board.

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No. Anything more than 5v will fry that sensor (and it will always display 255 from then on).

Did you get your sensor in an EZ-B developers kit? There is a little circtuit board in the cable on the one in the developers kit which is a 5v switching regulator.

If you didn't, you can buy the regulator from EZ-B, or just get an L7805 or similar for much less (they heat up, unlike the EZ-B switching regulator, but going 7.5 to 5v won't be too bad, and at 5 for ~ $3 without the international shipping, might be a better solution for you).

The V3 board had a 5v regulator on the VCC pins, but the disadvantage was that it couldn't drive high power servos and would brown out and/or overheat if you used all of the ports.



Alan, Are you saying the ultrasonic sensor I bought with the V3 will not work on the V4 without a special cable

Also, now my robot won't even power up. While measuring pin voltage a made a spark.



Unless you use 5V to power your ezb4 then yes you will need an inline voltage regulator for all 5V sensors (not just your ping)... The voltage regulator is sold in the store and is included in the developer's kit... I made about 20 of them by soldering a LM7805 5V voltage regulator into some servo extension cables... Cost me about $10 for about 25 of them off of eBay


Yes, you need a voltage regulator to use any 5v sensor with the V4 unless you provide 5v for the input (in which case your servos won't work well).

You probably just blew a fuse. There are two. A self resetting one in the EZ-B itself. Just give it some time and see if it turns back on. If not, then check the replaceable fuse in the Roli body. See for instructions.

Assuming it is OK and comes back up from one of those, I can help you out with the sensor.

You have a 3D printer, and I need some small parts. If you print me 2 of the small bits and one of the large bits for a rotation servo, I will send you an unopened HC-SR04 and an L7805 voltage regulator you can solder onto a cable for the HC-SR04.

Send me your snail mail address in email (my email address is in my profile) and I'll reply with mine.



Do you think I just need to wait for the thermal switch to reset? I am hoping that my easy B is not damaged. It would be helpful to know that there is that much difference between the two kits. Went to the trouble of 3-D printing the enclosure remounting the sensor in it I could've just bought the updated ultrasonic sensor from the store.


we posted simultaneously, so you may have missed my reply which pre-answers your question. Look at post #8.



When you measured the pin voltage you probably inadvertently shorted across the pins... If you're lucky you just blew a fuse or tripped the poly fuse... I dropped a screwdriver on one of my ezb4 boards and now port 9 does not work... Be careful


Alan, That sounds great. I have some of the parts printed up already. Show me which parts you need printed.

Email me at...


Fuse was blown. Off to autozone to get another.


@mstephens_42 .... That's good news... maybe you should get a couple, though....;)


Please follow the tutorial on the developer kit - the data sheet will explain the ports, voltages and other relevant data to prevent from potentially blowing up your ezb:)


DJ, Can you confirm my schematic....

I've killed two ping sensors due to my mistake trying to do this without the voltage regulator...

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If you now have a 5 vdc potential actually applied to your sensors you will be in good shape. All you need to do to verify this schematic is to use a volt meter and measure the voltage being applied to you sensors before you actually connect them.


Circuit looks right except I don't think the middle pin on the 7805 is the ground, but I don't recall if it is the left or right.

I'll look it up in the morning.

Happy New Year



Here's one electrical application using your 7805 hardware.

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One additional point that I will make is that due to the operating voltages that the EZB(4) are normally exposed to, the capacitors displayed (pictured) in the previous schematic may not be necessary.


@mstephens_42 Your diagram in post #17 is correct... All pinouts are correct... As mentioned, I have made about a dozen of these and they work great....


Richard and Alan, Thanks so much. I'll wire that up and try it out. One question I have is the output pin regulated to 5v in the ezb?

Alan, I'll get your parts printed.


The data pin on the analog and digital ports is 3.3V (white pin) the red pin (power pin) as mentioned equals whatever battery voltage you are using to power your ezb with... If you are using a 7.4 lipo then the red pin will be 7.4V as well... If you use a 12V battery then the red pins will be 12V... Here is the link to the ezb data sheet with all this info on it... EZB4 Data sheet


I was mistaken last night (blame adult beverages). The ground is tthe middle pin. Your diagram is correct.