attinyattiny85microcontrollerpcb-design
I have created a prototype PCB with an Attiny85 on board. This Attiny is programmed by the supplier before it is sent to the PCB manufacturer. I received my prototype on friday and it seems that the Attiny on the PCB has a clock speed which is much slower than mine on the breadboard.
Is the desired IC clock specification (e.g 8Mhz internal) not compiled into the HEX files one sends to IC supplier? Does it have to be specified separately?
You likely want something like a Tag-Connect:
They're available in 6 and 10 pin versions, with and without the plastic retaining clips. You can find them at places like Digikey. They are not cheap ($35), but you'd only need to buy a couple to program a ton of boards.
As a side note: I think when you say "jumpers" you really mean "headers". Headers are the pins, jumpers are usually blocks that short pairs of those pins.
An attiny will be fine for a single servo and adc sensor with the Arduino firmware. The things an attiny can't do that an atmega can has to do mostly with code space and amount of timers or interrupts. Your project is very small and not affected by this limitation.
As for developing a custom Arduino pcb, it's not that complicated. An Arduino is essentially just a breakout board for the microcontroller, with a regulator and usb to serial circuit attached, neither which are 100% required to be on board. Look at various bare bones Arduino which are no more than the microcontroller and a few passives.
Best Answer
The HEX files only contain the contents of the flash memory, not the fuses.
In addition to the HEX file you must also supply the values for the fuse bytes. Here is what Digikey requires when requesting pre-programmed parts...
I know this seems backwards and brutish, but so it goes. Most other vendors would prefer an email just giving them the hex values for the 3 fuse bytes. Your email might look like...
You can get these bytes from one of the many calculators on the internet, using the looking in the "device programming" dialog in Atmel Studio, or reading them from a working device using something like AVRDUDE.
Interestingly, the ELF file format can encapsulate both the flash and fuses in a single file. You can create one of these file in Atmel Studio in
Device Programming->Production Files...Unfortunately I have never seen an ELF filed used by a production programmer. Even AVRDUDE must be coaxed into use the individual values inside the ELF with a command line like...