HC08 In-circuit programming min requirements

[Bloodhound]

Hi All,

Well, I've just started my first project with a HC08 (HC08GZ16CF to be exact). However, I am a little confused as to just what is needed for in-circuit programming as far as production units go.

In the past I've used AVR's, these are dead simple to program in-circuit, with the HC08 it seems a little 'complex'.

All we want to be able to do is program the devices in circuit, they don't need to run debugging, just programming the flash in the end product.

I have the SofTec InDart design kit and from what I can see with that we are going to need a 16pin header on the PCB

Any advice would be much appreciated.

Thanks,

Ross

[bigmac]

Hello Ross,

I generally prefer not to include a programming header on the board because I think it unnecessarily exposes the pins of the MCU to the effects of possible static discharge with accidental contact.  I would usually provide a row of plated-through holes on the board.  During in-circuit programming, a suitable plug is located in the holes, and held in position with sideways pressure, to maintain temporary contact.

Assuming you need the ability to erase and re-program a previously programmed MCU, you would need to be able to enter normal monitor mode - this requires more connections than forced monitor mode - a maximum of nine, including Vdd and ground.  However, four of these require only static voltages of Vdd or ground.  If you can organize so your I/O circuitry applies the required voltages (pull-up or pull-down), these pins do not need to be extended to the programmer.  It would also seem that, it your application uses a 8 MHz crystal, you would not need to extend the OSC1 pin.

However, if you use the IRQ pin as an input, keep in mind that Vtst will be applied during programming.  It is quite possible that this voltage level could damage a connected device, or protection diodes within the connected device could prevent the proper Vtst level being realized.  Been there, done that!

Regards,

Mac

[Alban]

Hello,

Only a few pins of the 16-pin header are actually used.
For you to know which pins are important, refer to the Development Support chapter of the datasheet.
It will show you a table with the status need for each "special" pin to enter MON08= Monitor Mode.

Programming and Debugging use the same mode.
Depending on which pins you use on your application, you can dramatically reduce the number of pin needed to plug to the MON08 programmer, in your case SofTec InDart.

EDIT: I looked and if your part is not programmed previously, you only need to connect PTA0 and power to enter monitor mode. This is explained in page 276 and following of MC68HC908GZ16 Datasheet Rev.4.

Cheers,
Alban.


Message Edited by Alban on 2007-09-10 03:58 PM