AVR ISP Programmer....need crystal?

Hi there,

I wish to build an external programming board to extend the ISP programming capabilty over Arduino IDE…

Want to use a wide range of ATTiny and ATmega MCUs, like (ATtiny13, 85, 2313, ATmega8, 328, etc…).

The board should look like this (similar).

Using trough USBTinyISP Interface, same as on this picture bellow.

My question is,…

If I wish to upload Bootloader or Sketches to mentioned MCUs, do I need to implement
crystal oscillator and capacitors circuit to my external extender board (Target board).

Thank you for the answers! :wink:

If you want to bootload chips and set them to use a configuration with a crystal, yes.

Note also that you probably need a separate crystal for each chip - you can't have long traces connected to the pins on a crystal.

The crystal doesn't necessarily have to be the right speed, it just has to be there. I'd use 8mhz.

DrAzzy:
If you want to bootload chips and set them to use a configuration with a crystal, yes.

Note also that you probably need a separate crystal for each chip - you can't have long traces connected to the pins on a crystal.

The crystal doesn't necessarily have to be the right speed, it just has to be there. I'd use 8mhz.

So, so, then these boards and shields below are not good, or?!?

1).

2).

3).

4).

I'm confused a little bit now! :frowning:

If you're planning to only use the internal oscillator (8MHz or less) then you don't need an external oscillator. If you're planning to run you microcontrollers on more than 8MHz, you'll need an external oscillator. If you're going to do a board, I highly recommend to add a crystal socket, so you'll have the flexibility.

If you really want to just have one crystal for all microcontrollers, you'll have to add a driver circuit and feed the signal into the XTAL1 pin on the microcontroller

having designed a few programmers i find a crystal for the target is not needed. most commercial adapter boards do not use one either. a clock signal can be supplied by the programmer chip. arduino-as-isp sketches provide this signal and imo a better choice than usbtinyisp.

john1993:
having designed a few programmers i find a crystal for the target is not needed. most commercial adapter boards do not use one either. a clock signal can be supplied by the programmer chip. arduino-as-isp sketches provide this signal and imo a better choice than usbtinyisp.

So, If I make that kind of a programming board and will use with ArduinoISP then will be fine?
Only add crystal if I will put the MCU after to another custom application?
Can I program then the programming board trough 6pin Arduino ISP header or need to connect trough Digital pins?

Thanks!

You still need some way to supply a clock signal to the XTAL1 pin to program parts not set to use the internal resonator (eg, if you're setting it to use a crystal. You can do it with crystals, or with Arduino as ISP and distribute that 8mhz signal (but that's an extra wire, in addition to the normal 6-pin connector, or with another frequency source....

Point is, if you set the chip to use an external crystal or clock source, and don't have something that looks like a clock signal on XTAL1, the chip will not respond to ISP programming (symptom is signature reading as all 0's, same as some wiring errors)

beic:
So, If I make that kind of a programming board and will use with ArduinoISP then will be fine?

I use a Teensy running a modified ArduinoISP sketch for a programmer. It plugs into a little PCB with a six-pin header (some other pins are brought out for debugging, tuning, and clocking).

In my experience, "yes" is the answer to your question.

beic:
So, If I make that kind of a programming board and will use with ArduinoISP then will be fine?
Only add crystal if I will put the MCU after to another custom application?

yes. that is the easiest and most economical way to do it.

ps. technically arduino-as-isp is a sketch running on uno or promini and not the same as arduinoisp which is a commercial product using proprietary circuit. best not to confuse the two when choosing programmer in ide.

john1993:
yes. that is the easiest and most economical way to do it.

ps. technically arduino-as-isp is a sketch running on uno or promini and not the same as arduinoisp which is a commercial product using proprietary circuit. best not to confuse the two when choosing programmer in ide.

Ok, then, my last question...

Can I connect my external programming board trough Arduino ICSP 6-pin header and to program the target MCUs in external board like ArduinoISP or Arduino As ISP?

I don't wanna use the Digital pins for programming and the capacitor on the reset line, it will work that way?

beic:
Can I connect my external programming board trough Arduino ICSP 6-pin header and to program the target MCUs in external board like ArduinoISP or Arduino As ISP?

No. RESET is connected to the reset on the Arduino. It has to be connected to pin 10. Nick Gammon has an example cable on his website that breaks out that one connection.

Link please to the Nick Gammon example!

Just four keywords, all present in post #10, got me to Nick's page using a popular search engine. It would have taken less time for you to find the page yourself than to create your post asking for someone else to find the page for you. Being an optimist I assume you are being sociable and helpful to others rather than unbelievably lazy so, here you go...

https://www.google.com/search?q=nick+gammon+isp+cable
http://www.gammon.com.au/bootloader