Smallest Programming Connector, In circuit series programming.

Hello,

I am using the Atmel SAM3N00B microcontroller and the only way I can see to do in circuit serial programming is to use the 20 way JTAG connector.

However, this connector is too big for our production unit, and I wondered if there is a smaller, say 5 pin programming connector which I could use?


SAM3N DATASHEET:
http://www.atmel.com/Images/doc11011.pdf

Check out Section 19.2.4 of the doc you linked.. The six signals shown there are all thats needed, (oh plus VCC & GND).. total of 8 pins..

Also look up ICSP ports (Wiki linky for more details on how to do it with 5

On many occasions I've seen IR interfaces that couple to ICSP so the device can be programmed actually 'through the casing' of the equipment itself. No-touch, no-visibility, 100% waterproof etc....

Basically it's a serial-ICSP interface with an IR input front-end (as opposed to hardwired serial).

The IR interfaces are for Flash programming only, and cannot be used to set fuses or hardware (IE Crystal Hz, Clock divider, Brownout V, etc)
Most of those you will find a hardwired ICSP port, used in the factory, and the IR is used for Firmware updates in the field..

I can't imagine a properly designed field unit requiring anything other than firmware updates.....

You don't need an actual connector to do ICSP. Well, I imagine it might help if you actually needed 20+ connections.

If you only need 6 or 8, you can put your ICSP connections onto pcb pads. Preferably in a row or a double row. Then make a spring pin programming interface.

I'm sure you already knew that, but just FYI.

Hmm, not sure about SAM3, but most of the 'new' ARM MCUs support SWD in addition to full-blown JTAG. (2 signal wires, only)

Yeah, looks like SAM3 has it too. all you need are the pins SWDIO and SWCLK.

With the Project that i posted previosly (RF one) in this pic you can see the ICSP ports

The duel inline one is where we solder pins in for a more permanent connection (it's the Debug port) and only used for on the bench development and testing..
And the single file (7 hole) is used for mass production quick programming, and relies on temporary tension contact for the 20 odd seconds it will be used to flash the micro..

This one is the 4 wire STMS programming port (pluged into our Prototype dev board) and the Programmer is visible behind.


and here is a selection of ICSP/STMS Programmers in the dev workshop, If memory serves we have ~ 10 different programmers in total, (including a BIG 48 pin EEPROM programmer)..

Left: Renesas (E8a) 12 pin (Min required - 7)
Mid: AVR (ATJTAGICE2) 10 pin (Min required - 5) (the ribbon cable is actually 20 pin, but every second line is connected to GND for signal seperation)
Right: ST (ST-Link/v2) 20 pin (Min required - 4)
The major thing is that each different Uc requires a different programmer, and of course because one type cannot be used for each and every project, we have to have the luxury of been able to select the Uc that will best fit the project, with the lowest cost..

We have one product where the Uc uses only 6 IO ports, and only two carry digital data, the rest switch items on and off.. Quite pointless using the Uc in the first pic, that can drive a LCD display and has 32 IO ports. because it'll be a waste..

The absolute min pins you can use is 4.
GND, VCC, Clock (SWCLK) , Data (SWDIO).

However some Uc split the Data into separate Input and Output lines, (now need 5) and then others use Reset and NMI pins to put it into Bootloader mode (now at 7)

Most of the other pins are for extreme cases like if the Uc is set to use a external Crystal, two pins are used for Xtal1 & Xtal2, for clock syncing, Some Uc's take time to write to the internal flash and so add a REQ and ACK pins to prevent overrun. Also some Uc's need a higher V for programming the internal EEPROM, so add a VPP for these.

Then you need some signal separation so you pop a few GND line between critical data lines and you very quickly gut up to the 20 pins.. However there are specifically only 12 critical pins needed to cover all cases.

Right on, but you still need the initial setup to be done in the factory, so the board will still have a hardwired ICSP port, while it wont be accessible once fitted in final casing. In these cases it's also common for the board to be potted, and you never have access to the Hardwired port again..

Just like this meter project.. the Hardwired ICSP port gets buried in Grey Resin, and only the IR's and LCD stick out.. (Also note that apart from Firmware, the IR is also used for Upload and download of the recorded data)


I realy hope this post offers up all the info needed.. (i could get into it allot deeper if need be)