Again, I appreciate very much your kindness and helpful answers.

Phong.

I think that keeping the supply voltage in the range of 5V to 9V is a good idea, but I’m not 100% sure on what the cause of bootloader corruption could be. It seems to be quite rare, but it does occasionally happen.

For your robots, I’ve seen the PWR LED blinking on B+ and Pi 2 robots, but haven’t had the power off in response to a quick move, this would probably indicate that the motors are drawing too much current so it might be worth checking that they’re not obstructed in any way. Also, it might be worth swapping the powerbank conenctors around so that the 2.1A connector powers the mini driver, and the 1A connector powers the Pi. On the old model B we seemed to need the 2.1A connector to power both the Pi and wifi, but with the new B+ or Pi 2, I think that as long as you’re using a low power WiFi dongle like the edimax, you might be able to run the Pi and WiFi off 1A.

For your second robot, if there’s no Pi involved then 4xAA rechargeable batteries should be perfect.

Regards

Alan

What a brilliant advice! I have another RPi card and so I got to connect 4 GPIOs on RPi to SPI port of mini-driver and with resistors in between. The mini-driver is new like out of the box now. Thank you!

By the way, in order to avoid future corruptions of the boot loader, I guess I have to guarantee the supplying voltage is between 5V and 9V? How about lower than 5V?

In particular, I have two robots:
(1) One is the Magician chassis kit bought from this store. I use the TeckNet powerbank if 5V+2.1A for the RPi and 5V+1A for the mini-driver. Sometimes the robot suddenly power off if it moves quickly from idle. The PWR LED of RPi is frequently blinking (it means lack of V).
(2) Another one is assembled from one mini-driver and the Tamiya tank chassis. The mini-driver is responsible for the 2x motors, 2x servos, 1x bluetooh HC-05, and 1x IR Sharp sensor. Is there any problem if I power this whole stuff with 4x AA rechargeable piles?

Best regards,

Phong

Sorry for the delayed reply.

I have managed to flash an Arduino with a mini driver, but it was a while ago, and I remember it being tricky. Probably the best thing would be, if you have an Arduino, such as an UNO lying around, to use that, as it’s a bit easier. Alternatively, if you have some wires and some 1K resistors to use for current limiting you can use your Raspberry Pi by following the instructions here.

Hope that helps.

Regards

Alan

I have two dagu mini-drivers, an old (called it A) and a newer one (called it B). The A works fine for my 2WD Magician chassis robot. Recently I want to plug some more sensors and servors to A so that I reprogram the sketch. I tried to upload but failed many times. A very simple program is Blink (LED); I can upload smoothly to the B but not to A. The message from A is:

avrdude: stk500_recv(): programmer is not responding

Then I suspect that the bootloader of A is problematic (since there are several times the power of the robot suddenly off, maybe due to insufficient voltage or current). I followed your instruction to make B as a programmer to upload the bootloader via ISP to the A. All the parameters are correctly set: Board: Arduino NG/older atmega8, Port: /dev/ttyUSB0, Programmer: Arduino as ISP. I tried to clikc on Burn Bootloader many many times but they constantly talk to me:

avrdude: Yikes! Invalid device signature.

Double check connections and try again, or use -F to override this check.
One of out one hundred times the burning is silent and just output:

Binary sketch size: 4,884 bytes (of a 7,168 byte maximum)

I thought the bootloader is already on its place so I try to upload sketches to it using normal serial USB port but again:

avrdude: stk500_recv(): programmer is not responding

I have tried:
-Arduino IDE 1.0.4 and Arduino IDE 1.6.0 too, but no difference.
-Supply the USB with more power (I use two USB ports for instance) but no help

This is my setup to burn the bootloader to A via ISP, using B as the programmer:
https://drive.google.com/open?id=0B26_kd-0bahhNzVncVFRTlo0aEU&authuser=0

If I upload the simple Blink code to the programmer B, then after wiring the ISP, I have the both drivers blinking synchronously. That means the wiring is correct ?
https://drive.google.com/open?id=0B26_kd-0bahhTkgxTW5Hemw3TWc&authuser=0

This is the ISP connect on the programmer side:
https://drive.google.com/open?id=0B26_kd-0bahhMm5EWXQ1SzkwZU0&authuser=0

According to your instruction, one has to remove the jumper at D10 and plug the reset wire there, right?
and the ISP connection on the driver A:
https://drive.google.com/open?id=0B26_kd-0bahhTkgxTW5Hemw3TWc&authuser=0

Phong.

Yes, this shouldn’t happen with the Dagu version of the bluetooth module that we sell, which is designed specifically for the Mini Driver, but I can see how it might cause a problem for the HC-06.

Glad you got it working.

Regards

Alan

I thought that the bluetooth slot is straightforward and just plug the HC-06 in. But I was wrong. The RX on the board has to be connected with the TX of the HC-06 and the TX (board) -> RX (HC-06). I learned this from a blogpost on Sparkfun:
https://learn.sparkfun.com/tutorials/serial-communication
It is necessary to wire the bluetooth module using jumperwires (with or without breadboard) and not directly to the mini-driver.

Now it works like charms.

Thank you!

Try leaving the HC-06 detached whilst you get serial to work. Shouldn’t have any effect, but perhaps it’s wired the wrong way round.

Please double check the connection of the bluetooth module to check that it is plugged into the mini driver the correct way round.

In the mini driver code, the baud rate should be 9600 (Serial.begin(9600)). This is because the baud rate of the bluetooth modules are 9600 by default, although this can be changed later by sending special serial commands.

It might also help if you send data periodically from the mini driver using Serial.println see if you can see anything on your phone.

Regards

Alan

int led = 13;

// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(led, OUTPUT);
Serial.begin(57600);
}

// the loop routine runs over and over again forever:
void loop() {
if (Serial.available()) {
char cmd = Serial.read();
if (‘f’ == cmd){
Serial.println(“Command recognized”);
digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(led, LOW); // turn the LED off by making the voltage LOW
}
else
{
Serial.println(“Unrecognized command”);
digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait for a second
digitalWrite(led, LOW); // turn the LED off by making the voltage LOW
}
}
}

So I detach the HC-06 and attach the USB2Serial cable into the mini driver and upload the code above. First I test the serial connection by openning the Serial Monitor and type “f”, then the blue LED on the mini driver blinks for a second. So the (wired) serial connection works!

Then I detach the USB cable and attach the HC-06. The board is powered by a battery source (5V 1.2amp). Now the bluetooth LED is blinking. I either use BT BotCar or BlueTerm on my smartphone to bind with the HC-06. The bluetooth LED stop blinking; this means the pairing is successful. Then I type “f” but see no respond on the LED of the mini driver. I guess the Serial connection is not available.

I set the baud rate to either 9600 or 57600 but no help.