Dawn Robotics Forum

Re: problem with dagu mini driver stopped working

2015-11-03T17:28:52+01:00

Hi there,

Welcome to the forums.

In answer to your questions.

1. That jumper sets the voltage that is passed to the central voltage pin for the set of 3 pin connectors that run down the same side of the mini driver as the power switch. The default setting is to have +V=5V which means that all sensors and servo motors connected to those pins will run off 5V. For most situation this will be fine, but the problem is that the 5V is provided the the linear regulator on the mini driver which can provide a maximum of 1A current. In situations where you're connecting multiple servo motors to the mini driver that require a higher voltage, or which will draw more current then you have the option to run them directly off battery voltage by moving the jumper so that +V=+BAT. If you choose this option then it requires some care so that you don't damage your hardware, basically

The maximum input voltage to the mini driver should not exceed 9V
If VBAT is higher than 5V then be careful not to attach 5V sensors to those pins, you may fry the sensors

More information can be found in the mini driver manual.

2. When connecting the Pi to the mini driver. The Pi (running at 3.3V) needs to be protected from the mini driver (running at 5V). The easiest way to do this is to put 1K resistors on the connecting wires (as shown on the pi_isp page). This doesn't actually shift the voltage down. What it does do though is limit the current that flows into the Pi GPIO pins (I = V/R), the current is what would burn and damage the Pi. Now, this is a rather hacky solution, which has never caused me any problems, (I've flashed a lot of Arduino compatible devices like this using a number of Pis) but you may be uncomfortable doing it. If you'd like a proper level shifting solution, then I'd suggest using something like Adafruit's level shifting board.

Hope that helps, and gives you some useful information.

Regards

Alan

Statistics: Posted by Alan — Tue Nov 03, 2015 5:28 pm

Re: problem with dagu mini driver stopped working

2015-10-30T18:41:21+01:00

I don't have electrical engineering knowledge. Please help me to understand how to flash Dagu Mini Driver using Raspberry Pi 2 Model B without damaging any of devices.

1) Dagu Mini Driver can be powered from micro-USB and from Battery +/-. Near power switch it have V selector, which has two modes: +5V and Battery. From information on back side seems Battery = Vin? Seems I have default mode +5V and never changed it. How that comes that if I connect batteries to Battery + and Battery - and turn switch On it works even then V selector is +5V? Then that V selector does, that it is for?
2) In pi_isp guide there is instruction to level shift to +3.3V. I completely don't understand this. What device should I level shift to 3.3V: RPi or MiniDriver? How do I do level shifting?

Statistics: Posted by hobbyrobots — Fri Oct 30, 2015 6:41 pm

Re: problem with dagu mini driver stopped working

2015-10-07T17:45:46+01:00

Hi there,

Glad you made progress with this eventually. Please let me know if you have any further problems. Also, please feel free to email helpdesk@dawnrobotics.co.uk if you need a more timely response.

Regards

Alan

Statistics: Posted by Alan — Wed Oct 07, 2015 5:45 pm

Re: problem with dagu mini driver stopped working

2015-10-06T23:04:34+01:00

Well I tried everything. Changed the pi / sd card. I connected the arduino directly to the PC and managed to upload the sketch. Reconnected everything and got some success. The motors were working but not the pan and tilt and even stranger the motors would react on the pan/tilt joystick. Then realized that older pi was using a different version of the firmware. Tried to upload the newer version and wouldn't upload and stopped working again. Moved back to the newer pi version 2 and was back with the /dev/ttyUSB0 not existing. After a lot of ffaffing lsusb and dmesg connected the dagu mini driver to the PC and tried to upload. No Com3. Anyway to cut a very long story short it was the cable between the pi and the dagu mini driver. The first time I had connected to the PC I had used a different one. But then I had reconnected the pi with the faulty cable. I hope I've not been boring but I thought it might help someone else who finds themselves in a similar situation.

Statistics: Posted by danijazz — Tue Oct 06, 2015 11:04 pm

Re: problem with dagu mini driver stopped working

2015-10-03T22:57:16+01:00

I went ahead and flashed the bootloader. This came back with successful message. The firmware seems to be uploading correctly but still not working as it should. Seems to be the connection between the Raspberry pi and the dagu mini driver - ttyUSB0 doesn't seem to exist. Any ideas?

Traceback (most recent call last):
File "robot_control_test.py", line 41, in
connected = miniDriver.connect()
File "/home/pi/raspberry_pi_camera_bot/mini_driver.py", line 673, in connect
self.connection = Connection( self.SERIAL_PORT_NAME, self.BAUD_RATE )
File "/home/pi/raspberry_pi_camera_bot/mini_driver.py", line 462, in __init__
self.serialPort = serial.Serial( serialPortName, baudRate, timeout=0 )
File "/usr/lib/python2.7/dist-packages/serial/serialutil.py", line 260, in __init__
self.open()
File "/usr/lib/python2.7/dist-packages/serial/serialposix.py", line 276, in open
raise SerialException("could not open port %s: %s" % (self._port, msg))
serial.serialutil.SerialException: could not open port /dev/ttyUSB0: [Errno 2] No such file or directory: '/dev/ttyUSB0'
Exception AttributeError: "Connection instance has no attribute 'serialReadProcess'" in > ignored

Statistics: Posted by danijazz — Sat Oct 03, 2015 10:57 pm

Re: problem with dagu mini driver stopped working

2015-09-30T19:47:17+01:00

I've got a raspberry pi and wires but not encoders. But I'm not sure where the encoders are used as I can't see this mentioned in the instructions. I don't have resistors either but should be able to get hold of some. Other than 1k is there any other spec I need to look out for. Sorry if these questions are really basic.

Statistics: Posted by danijazz — Wed Sep 30, 2015 7:47 pm

Re: problem with dagu mini driver stopped working

2015-09-29T19:13:56+01:00

Hi there,

Do you have a Raspberry Pi? If so, you can reflash the bootloader using instructions here. If you don't have access to suitable wires with encoders, then if you can send your order number to helpdesk@dawnrobotics.co.uk then I can send some out to you.

Regards

Alan

Statistics: Posted by Alan — Tue Sep 29, 2015 7:13 pm

Re: problem with dagu mini driver stopped working

2015-09-27T22:34:35+01:00

I've just got the exact same problem as the original post. I have connected the mini driver to my pc and tried to upload the blink sketch as suggested and it has failed. Like you say it looks like the bootloader has got corrupted and unfortunately I don't have another arduino nor a programmer.

Statistics: Posted by danijazz — Sun Sep 27, 2015 10:34 pm

Re: problem with dagu mini driver stopped working

2015-06-24T19:01:59+01:00

Great stuff, thanks for letting me know.

Regards

Alan

Statistics: Posted by Alan — Wed Jun 24, 2015 7:01 pm

Re: problem with dagu mini driver stopped working

2015-06-23T21:40:45+01:00

Hi Alan

The new mini driver arrived today - thanks for this. I have assembled everything again and... hooray - a working robot!

I'll have a go at the old mini driver when I get time.

Thanks for the support,

Ray

Statistics: Posted by relast — Tue Jun 23, 2015 9:40 pm

Re: problem with dagu mini driver stopped working

2015-06-22T17:28:26+01:00

Hi Ray,

We've sent out a replacment mini driver today, so it should be with you in the next couple of days. I've tested it this morning on one of our dev kits and the firmware uploaded without any problem, so it's currently programmed, ready to go.

When testing on your robot, could you please begin by powering the Pi with your 2A supply, and also connecting some AA batteries up to the mini driver? The AA batteries will just be to power the motors on the mini driver, and so just 4xAA batteries rechargeable, or non-rechargeable should be fine.

If that works then the next thing would be to try running the robot completely off batteries. My recommendation would be to use 6 good rechargeable AA batteries.

Any questions or problems, please let me know.

Regards

Alan

Statistics: Posted by Alan — Mon Jun 22, 2015 5:28 pm

Re: problem with dagu mini driver stopped working

2015-06-21T20:10:00+01:00

Hi Alan

Yes - I think it would be best to get the robot up and running now. Thanks for the support and for sending out a new driver, I'll let you know how I get on and whether I manage to fix the old one later.

Regards

Ray

Statistics: Posted by relast — Sun Jun 21, 2015 8:10 pm

Re: problem with dagu mini driver stopped working

2015-06-20T19:40:07+01:00

Hi Ray,

Sorry for misunderstanding about whether you'd put the bootloader on. I did find it hard to believe that you would be doing the more advanced thing (i.e. using the Uno as an ISP to write programs directly) but then not putting the bootloader on.

We could try debugging further by running avrdude from the command line (the program that the IDE is using behind the scenes to flash bootloaders etc) but I think it's probably easier to assume for now that the mini driver you have is duff, and I'll send out a replacement mini driver as promised on Monday.

So please, take a break for now, and if you're interested later on in the week I can point you towards the avrdude commands for flashing from the command line (if you haven't looked at it already) to see if we can revive your mini driver so you can have 2.

Regards

Alan

Statistics: Posted by Alan — Sat Jun 20, 2015 7:40 pm

Re: problem with dagu mini driver stopped working

2015-06-20T18:58:03+01:00

Hi Alan

Thanks for persevering here. I should have made it clear earlier, but I always put the bootloader back on using the Uno, before I tried again with the mini driver attached to the pi.

Anyway, I thought I'd give it another go, but no luck. The bootloader burned correctly, lots of flashing LEDs on both boards and a success message. Reconfigured and tried to download Blink directly, PC to mini driver (reinstalled the drivers) and I still get the out of sync message. I followed your instructions to the letter - twice. I got to this point before too as that is when I found I had to use the Arduino IDE 1.0.1 to be able to burn the bootloader.

It's all a bit strange. I know I keep on about not being able to download a sketch over USB, but the mini driver does at least enumerate as a COM port, so some functionality is there...

Regards

Ray

Statistics: Posted by relast — Sat Jun 20, 2015 6:58 pm

Re: problem with dagu mini driver stopped working

2015-06-20T16:07:08+01:00

Ah,

So when you're uploading blink using the Uno, that will be overwriting everything on the mini driver chip (the atmega8). The bootloader will therefore not be on the Mini Driver and so you won't be able to upload a sketch to the mini driver over USB. That would explain why you're getting results that make it look like the bootloader is corrupted, it's simply not there.

If you're able to upload sketches via the Uno though, i.e. the Uno is acting as a programmer, then I think you're about 90% of the way there. The steps to reflash your bootloader on the Mini Driver should be

Connect the Uno to the PC and the Mini Driver to the Uno
Open the Arduino IDE
Select Tools > Board > Arduino NG or older w/ATmega8 (i.e. you're selecting the board at will be programmed)
Select Tools > Programmer > Arduino as ISP
Select Tools > Burn Bootloader
Wait a while...

Once all that completes, if you were successful then you should be able to program the mini driver from the Arduino IDE on both the PC and the Pi using just a USB cable i.e. no Uno required. Although one other thing I've thought of that you may need to do. If you're on Windows, you'll need to install drivers for the Mini Drivers USB to serial chip. A link to the drivers can be found in the Useful Links section of the Mini Driver product page.

Regards

Alan

Statistics: Posted by Alan — Sat Jun 20, 2015 4:07 pm