I want to design a bare-minimum board based on the Atmega328. I want to be able to use chips without a bootloader since they are cheaper. I want to save space and not have the ICSP connection on my board at all. I do need the FTDI chip for future updates.
So my question is, can I burn a bootloader directly from a USB connection (connected to the FTDI chip connected to the RX and TX pins on the 328)?
szangvil:
I want to design a bare-minimum board based on the Atmega328. I want to be able to use chips without a bootloader since they are cheaper. I want to save space and not have the ISP connection on my board at all. I do need the FTDI chip for future updates.So my question is, can I burn a bootloader directly from a USB connection (connected to the FTDI chip connected to the RX and TX pins on the 328)?
No you can't. Only a bootloader program already installed onto the chip knows how to program a sketch via the USB serial link. So you have to first burn a bootloader onto the chip or buy a chip that has the bootloader already burned into it.
Lefty
Thanks.
How do I know what bootloader is burned into a chip (and if one is burned at all)?
Often times you can tell by watching an LED on D13, see what kind of link sequence it is doing.
You can design your board to not have an ICSP header, but just make a breakout cable to connect the programmer to the appropriate pins to program it. Make your design to not have D11-12-13 used as inputs (instead be outputs to other devices) to eliminate signal contention.
Or program the parts before mounting them on the board.
Sound more simple to buy the chip with a bootloader already burned in.
But how can I be sure that the chip I buy (from mouser)has a bootloader?
szangvil:
Thanks.How do I know what bootloader is burned into a chip (and if one is burned at all)?
Well if you buy one preinstalled the vendor will state that it has a bootloader and which 'flavor'.
Lefty
szangvil:
Sound more simple to buy the chip with a bootloader already burned in.But how can I be sure that the chip I buy (from mouser)has a bootloader?
I don't think mouser sells them with a bootloader, but I could be wrong. If a given vendor has that option (bootloader preinstalled) it will clearly state so in the description. The ATMEL folks don't manufacture them with a bootloader so it's only vendors that can add that option.
Lefty
If you want to buy pre-bootloaded parts, you can get them here inexpensively and with low shipping costs in the US, with a choice of bootloaders.
Even has a picture showing one hooked up as a very minimal design.
szangvil:
I want to design a bare-minimum board based on the Atmega328. I want to be able to use chips without a bootloader since they are cheaper. I want to save space and not have the ICSP connection on my board at all. I do need the FTDI chip for future updates.
Are you sure that USB/FTDI is smaller than a six-pin ISP header?
Thanks for all the info.
Headers can be anything, such as jst.com ZH line of 1.5mm pitch connector.
http://www.jst-mfg.com/product/detail_e.php?series=287
Mating cable can have pins crimped on that an FTDI Basic can mate with for programming for example.
I must have the FTDI since I want a user to be able to update the software with only as USB cable. So the FTDI is a must.