Arduino BT w/ ATmega 186 -> ATTINY85

Hi, As the topic states, this case is for the Arduino Bluetooth to serve as an ISP programmer. I like to know if I can use it considering the pin outs are different from the ones of the Arduiono UNO and similar.

I'm looking at this sketch:

There are a couple of diffenrences between that and this:

Pin 7 is reset on the BT.

But the main question is where to connect the capacitor?

Any hints will be really appreciated. /a

Hi,

armadillo:
As the topic states, this case is for the Arduino Bluetooth to serve as an ISP programmer.
I like to know if I can use it considering the pin outs are different from the ones of the Arduiono UNO and similar.

The pins of interest are the same…

http://www.arduino.cc/en/Main/ArduinoBoardBluetooth
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication, which, although provided by the underlying hardware, is not currently included in the Arduino language.

Those four plus 5V and GND are connected to the target.

But the main question is where to connect the capacitor?

The schematic from the ArduinoBoardBluetooth is empty and I don’t have Eagle so I can’t access the schematic. Assuming the auto-reset circuit is similar to most Arduino boards, the capacitor is connected between the RESET pin and 5V GND.

Hi CB,

If 'im not wrong that capacitor goes between GND and the RESET pin. On the BT case PIN7.

"We’ll also connect a 10 uF capacitor between reset and ground on the Arduino board as shown in the diagram (the stripe on the capacitor that’s marked with a negative sign (-)."

According to: http://hlt.media.mit.edu/?p=1706

But what worries me most (allow my ignorance) Is this part:

"The capacitor prevents the Arduino board from resetting (which starts the bootloader), thus ensuring that the Arduino IDE talks to the ArduinoISP (not the bootloader) during the upload of sketches."

Since the Arduino BT uses soldered 168 MCU, i'm afraid of breaking/corrupting the bootloader...

I'm ready to try to flash some ATTiny85 i got, but since this is my only arduino board, and it was not that cheap.. I'm a bit doubtless.

Could you help me understand better the real risks?

Thanks in advance, /a :S

armadillo: If 'im not wrong that capacitor goes between GND and the RESET pin.

Yup. Sorry about that.

On the BT case PIN7.

As far as I can tell that is not correct. I believe pin 7 is used by the AVR processor to reset the Bluetooth radio.

Regardless of the intended purpose of pin 7, there should be no need to have anything connected to it when programming an ATtiny processor.

Since the Arduino BT uses soldered 168 MCU, i'm afraid of breaking/corrupting the bootloader...

I can't imagine that happening in this situation.

Could you help me understand better the real risks?

Including series resistors (220 ohms or higher) on the SPI lines (MISO, MOSI, SCK) is a good safety precaution. If there is a wiring or programming mistake, the resistors limit the current to a safe level for both sides.

OKE thanks for the 220ohm hint. Looking at this schematics, and from the little i know: http://arduino.cc/en/uploads/Main/arduino_bt06.pdf

Seems like the only reset is the push buttom.. no pins assigned.. other than #7 that resets, as you said, the BT module.

So I guess that there's no way to:

"Prevent the Arduino board from resetting (which starts the bootloader), thus ensuring that the Arduino IDE talks to the ArduinoISP (not the bootloader) during the upload of sketches"

Unless there's some other way to force this.. but I haven't found much more doc about it yet...

Physical pin 5 on the ICSP header (the six male pins next to the reset pushbutton) is RESET... http://www.arduino.cc/en/Main/ArduinoBoardBluetooth

This shows the location of pin 5... http://www.batsocks.co.uk/readme/isp_headers.htm