MC68HC08 - MC68HC908 Resource & links page
Auf der Suche nach einem möglichst preiswerten USB-Expander für Experimente mit externer selbstgebauter Digital-Hardware, der aber nicht ganz so spartanisch wie der FTDI-Chip, also auch programmierbar sein sollte, bin ich auf die S08JS8/16 Familie gestoßen. Hat, wie viele andere neuere USB-Microcontroller auch, einen USB-Bootloader integriert, sodaß man fast nur noch den Chip braucht und kein Programmiergerät. Hier ein erster Test von mir: Sieht so aus, als müsste da Atmel nochmal nachlegen, denn der Freescale-Chip kostet nur ca. halb soviel wie die Chips der vergleichbaren AT90USB-Serie und die FTDI-Chips sind noch teurer.

Just for Metrowerks HC08 C Compiler Demo.

- MON08 is a P&E tool (

If you need documentations and application notes about your processor and peripherals, go to the following websites: : an all in english hc08 developpers oriented website, with several examples, forums, databases, links etc... about the HC08 family : the motorola official website

If you need some specific samples or hardware implementation advices, you can contact the motorola online help line:
_ go to the motorola website:
_ then, in the main page, there is a list on the left side, select the entry 'technical Support' and then, 'technical helpline'.
_ then simplysign up (for free) and ask your questions there.

68hc08 programming:

hardware compatible with P&E use ideas from :

(max232 + 1 diode) A simple 68HC08 "programmer" board WWW page about Motorola 68HC08 microcontrollers

Free Codewarrior for HC08

Just to let those interested know: Metrowerks has released a 'Special Edition' of it's Codewarrior IDE for free for Motorola HC08! The compiler is limited to 4K, but an upgrate to a full compiler is only $US500 (much better than the original $US2000 they were asking). Offer ends mid June 2002 I think...

Codewarrier limited (to 4K code) edition for free:

You have to request a key to get it to work to 4K it is a 125M download.

I understand that it's a 90 days limited demo

Questions and Answers

68HC908 monitor problem

I have started a project using the 68HC908JB8 Motorola microcontroller. But having major problems getting the device into monitor mode. From what I have read in the data-sheet & building the circuit as used in the Motorola USB reference design (DRM002/D). To enter monitor mode certain pins have to be pulled high & low and 7-10v needs to be applied to the IRQ pin. I have downloaded the HC08SPRG.EXE Dos programming tool. And tried to program the device using this programmer, but with no success.

I run the programmer, reset the 68HC908 and the programmer reports the return value was 0x00 and an error of "device not calibrated". If I change the baud rate to some to a really low value like 1200 the return value becomes 0xf1.

Cannot any one give me some advice if their have come across this problem before, or any advice would be helpful.

answers or hints:
The baudrate is fix and depends from the crystal used in your target. Read data sheet for the "monitor rom" section. There is no connect if you not hit the correct baudrate. Some targets can use DTR or RTS to switch to monitor mode automatic. Try to make shure, that IRQ has 9V when there is a rising edge at the reset pin. Some power supplies have a slow rising edge and CPU starts much before IRQ has reached 9 Volt.

Make shure you have the correct security code. If failed, the CPU locks and all flash memory locations show 0xAD. The lock cannot removed with
a reset button. This needs power on reset. Plug off power supply and short circuit the secondary to make shure the supply is below 0,1 Volt and discharge all buffer capacitors.

Furthermore it can be recommended to try the free download of the more advanced programmer prog08sz at what also offers some diagnostic display in case of link problems


Good point on the power supply (not reaching 9V before the chip starts up). I find that the most reliable way to enter monitor mode is to put high voltage on the IRQ pin, then completely depower and repower the chip. Or, a neat trick the sample board uses, grab RS-232 levels and regulate them down to the 8-9 volt range. That way the 9V is always there when the serial port is active.

The baud rate is 9600, I believe (since the crystal has to be 6MHz for the internal USB functions to operate). And pemicro's tools are pretty good; never had a problem with them.

One thing to keep in mind: don't ever let any voltage higher than 11 volts hit the IRQ pin. Do it once, by accident, and you will never be able to enter monitor mode again. The chip will still work fine, but it will stay right where you last programmed it. I've considered using this as another layer of security, but who knows what really happens in there? Nothing you'll ever find out in monitor mode. So, you may have accidentally put too much voltage on that pin at some point.
Check over your circuit carefully. The Motorola reference design (I own a commercially-produced version of that board, in addition to my own circuits) has an 8V zener diode to regulate the voltage. If your circuit is exactly like the reference design, and still doesn't work, consider changing out the microcontroller.



Retour la page d'accueil

Mise Jour le : 20 août, 2012

Email :