Connecting 2x5 connector to Atmega8

Go To Last Post
27 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

For my project I've bought a Isp programmer(€7.95), but now I don't know how I have to connect that ISP programmer. I mean which pins to which uC pin?
I have the following connector pins

MOSI     VTG 
NC       GND  
RST      GND 
SCK      GND    
MISO     GND 

I couldn't find many information on the internet.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

you can find the information in the M8 datasheet.

Look for "memory programming --> serial downloading"

Quote:

??? I couldn't find many information on the internet. ???

Klaus
********************************
Look at: www.megausb.de (German)
********************************

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Did you look in the datasheet for the Mega8? The pinout drawing will show you which pin is SCK, etc. Assuming you're using the DIP package, then
MOSI = 17
RST = 1
SCK = 19
MISO = 18

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

OK I have the datasheet of the Atmega8, but not how to connect it which pin to which pin, that I couldn't find on internet

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I see 4x GND on my connector and x2 at the mega8. And I don't see a NC and a VTG pin on the mega8

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

NC means "no connect", so you don't connect it to anything.
VTG is your target voltage or the Mega8's VCC (DIP pin 7).
All the GND's should be wired together, so the 4 pins on the ISP connector go to both 8 & 22 on hte Mega8.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

you can conect all gnd to one

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks,

http://tuxgraphics.org/electroni... found that website, I thinks that can help me too!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Me again,

I've connected all wires to the good pin, but I can not connect to the chip with my isp-programmer with ponyprog or any other program. 'Device missing or unknown device'. I checked all wires and don't see any ..... Maybe the problem is, the voltage between the 'vtg' and the 'gnd' is not more then 1.5v. That has to be 5v?

Last Edited: Tue. Oct 24, 2006 - 09:33 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

what about supply voltage and clock?

May we see your wiring? picture/schematic/draft

Klaus
********************************
Look at: www.megausb.de (German)
********************************

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ah, the isp programmer is an easy build programmer. I bought a self-make programmer 'http://www.aavrs-nl.nl03.members.pcextreme.nl/index.php?p=55'
I have an ATmega8 that one needs an external clock?

Maybe the problem is, the voltage between the 'vtg' and the 'gnd' is not more then 1.5v. That has to be 5v?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I made a photo of my wiring.

http://avr.naffets.nl

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

As Klaus said above.
You still need an external supply voltage of 5V to run the ATMega 8.

Ken

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Ok, the pc also gives 1.5V. When I connect 5V to the mega8. There is 6.5 volt. So I have to disconnect the vtg pin of the programmer? And what to do with the gnd's?

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

Have you had a look at this reference ?
https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=33265
Pretty sure this is the setup you are using.
This may help or answer what is going on.

VTG should only be 5V(from an external regulated supply) connected to ATmega 8 pin 7 (VCC) then through a diode will drop to approx 4.4V or 4.6V to 74HC244 pin 20.
The GND should be common to the ATmega 8(pin 8 & 22), 74HC244(pin 10) & the DB25 connector (pin 20,21,22,23,24,25).

Still puzzle about the PC giving the 1.5V.
Where is this appearing(I know you said at the VTG) but which pins on the DB25 or the 74HC244 pin ?

Ken

ps. might be a good idea to connect the AVCC pin 20 to VCC pin 7 on the ATmega 8.

Edit 1

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

and a capacitor on VCC and GND next to the AVR is essential.

A look into the datasheet is as essential too!!!

Klaus
********************************
Look at: www.megausb.de (German)
********************************

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

After a brief look at the picture of your wiring you still need:

    A Power Supply (Pg of the Datasheet A clock signal (Page 25-32 of the Datasheet)

As Klaus suggested the Mega 8 datasheet http://www.atmel.com/dyn/resources/prod_documents/doc2486.pdf is an essential read.

Ben
-Using IAR (& ocasionally CodeVision)
0.7734
1101111011000000110111101101

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks all!

This is a kristal I can use? http://www.voti.nl/winkel/catalog.html?X-16M
(both are pages are dutch, but maybe you recognice the picture)

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

i think you can use this.

But you have multiple clock options. Read the datasheet.
You can use other options as well. The easiest is the internal RC clock. then you don´t need additional parts.

Take care of setting the fuses right.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I took a good look at the datasheet, but I don't understand how to connect the internal RC clock.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Have you added a power source?

Ben
-Using IAR (& ocasionally CodeVision)
0.7734
1101111011000000110111101101

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

Quote:
but I don't understand how to connect the internal RC clock.

it is INTERNAL, so you can not "connect" it like a wire to a pin.
You must set the clock fuse bits.

Klaus
********************************
Look at: www.megausb.de (German)
********************************

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

OK, thanks. I tought I had to set or connect some pins of the mega8 to each other.
Then I don't have to set the 'fuse bits', because I read it is set to 1Mhz.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi

Quote:
but I don't understand how to connect the internal RC clock

It's already built in the chip, just program the correct fuse for it.

Ken

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I haven't read the data sheets on the mega8 in detail, but I know that on the mega88, the internal RC oscillator is enabled by default. All you need to start programming the chip is to connect the ISP interface discussed above, and VCC and GND.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yes, and I have to add a power source.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Edit: already answered on 2nd page.