The monitor mode of MC68HC908JW32

[jjl3]

I created a board of MC68HC908JW32.

but after I entered monitor mode of MC68HC908JW32 only one time,

I have not entered monitor mode of MC68HC908JW32 anymore.

I measured Vtst is about 8.2V.

there is reset button on my board.

when I connect Vtst to the pin IRQ,

after power on this board,

I use oscilloscope to measure the pin RESET and the pin OSC1, OSC2.

this pin RESET is always low and the crystal 9.804MHz can't work.

when I pull up the pin IRQ to 5V,

after power on this board,

I use oscilloscope to measure the pin RESET and the pin OSC1, OSC2 again.

this pin RESET is high and the crystal 9.804MHz can work normal;

if when I switch the pin IRQ to Vtst at this time,

I found the crystal 9.804MHz stop working at once,

but the pin RESET is still high.

I can't understand what happen.

please help me!

thanks a lot in advance!

best regards

jjl

[jjl3]

this is the difference between version 3 and version 4 & 5.

[RockyRoad]

I've turned in a correction to the docs group...

Thanks for pointing out the error. I'm sorry that you had to find it the hard way.

- Rocky

[jjl3]

Mr peg

thanks for your help!

I am so happy that my board works normal.

I made mistak connect external oscillator to pin OSC2.

below is my conclusion, I hope it is useful for others.

1. To enter the monitor mode of JW32,

   the external oscillator must be used, but crystal.

2. 4.9152MHz or 9.8304MHz is ok.

3. the pin assignment in datasheet of JW32 is wrong in version 4 and 5. 

best regards

jjl

[peg]

Hi jjl3,

Glad to be of some assistance!

Perhaps you could describe how to fix the pin assignment drawing, as I'm still confused.

Or post the correct one from the old manual.

Regards

Peg

[jjl3]

Mr peg

thanks for your suggests!

just now I tried to connect 9.8304MHz oscillator directly to OSC1,

but it is very despond, I can't enter thr monitor mode.

tomorrow I will go out to buy 4.9MHz oscillator to try as your suggests.

this is my hobby,

so the local agent of Freescale would not like to give me support.

thanks for your help!

best regards

jjl

[jjl3]

Mr peg

the pin asssignment in version 3 is different from version 4 and 5.

I created symbol according to version 3.

If I am right, I still have problem on how to enter monitor mode.

whether we must use oscillator,but not crystal?

when to enter monitor mode.

best regards

jjl

[peg]

Hi jjl3,

OK, I read this section myself now and here is what I found.

This device has max rating for crystal and external oscillator of 4MHz. You are using either 8 or 9.8MHz. This is wrong!

The USB section is designed for use with a 4MHz crystal!

You can only use a crystal for monitor mode entry (4.9MHz) when the device is blank!

If the device is not blank you must use an external (canned) oscillator or either 4.9 or 9.8MHz!

So your MON08 setup pins are correct in your schematic for 9.8MHz but you have to use an oscillator and not a crystal!

So here is what I would do:

Mount a 4MHz crystal and support components right near the chip and throw away the switch etc.

Mount a 4.9MHz canned oscillator nearby that can be linked into OSC1 when you need MON08.

It will override the crystal frequency.

Change your pullup on PTC1 to a pulldown to select the right division.

Using 4.9 rather than 9.8 allow blank forced monitor entry as well!

Regards

Peg

[jjl3]

Mr peg

the pin assignment are same in version 4 and version 5 of datasheet..

I also think the pin assignment is standard,

so I didn't took more care,

when I created symbol of JW32 in schematic and in layout.

I will check it with freescale,

then post result .

thanks !

best regards

jjl

[jjl3]

Mr peg

yes, I am making OSBDM so that I can get familiar with HC08 and HCS08 family.

the pins IRQ and RESET are pin 47 and pin 48 respectively ?

In my schematic they are pin 37 and pin 38 respectively.

perhaps it is why I connect Vtst to JW32, the crystal can't work.

8.2V exceed the permitted voltage on other pins very much.

thanks for your warm help!

best regards

jjl

Message Edited by jjl3 on 2006-12-0101:30 AM

[peg]

Hi,

Another thing just occurred to me.

The IRQ pin in order to allow Vtst to be applied does not have the usual diode protection to rail.

If you can apply 8 or so volts to this pin without significant current flowing then this pin must be IRQ!

Regards

Peg

[jjl3]

Hi, all

I downloaded a newest datasheet of JW32,

but I found the order of pin is different between in shcematic and in layout.

please see attached file.

[peg]

Hi,

Oh Dear!

My best guess would be that the pin assignment drawing is correct as far as what number is what function, just layed out wrongly.

How does this tie in with the old document?

I'm sure they would not change the pin assignment without a part number change.

Actually what pin is what number is covered by standards and goes around the chip CCW from the corner that is bevelled or marked in this case.

Regards

Peg

[jjl3]

some tests on my board:

1. to reduce the voltage of Vtst to 6.3v

   power on system, crystal work normally.

   press and release reset button, crystal also work normally.

    but can't enter the monitor mode.

2. to reduce the voltage of Vtst to 6.8v

   power on system, sometimes crystal work normally.

   but press and releas reset button, crystal stop at once,

   can't enter the  monitor mode.

3. to reduce the voltage of Vtst to 7.5v

   power on system, crystal doesn't work.

   can't enter the  monitor mode. 

[peg]

Hi jjl3,

Check the manual for JW in the Monitor section, there should be a table of requirements for monitor entry, for both blank and non-blank.

Usually blank means no high voltage required.

Also a reset is not good enough, you need a power on reset with the conditions present to get in.

Regards

Peg

[peg]

Hi jjl3,

I downloaded the JW manual just now. All the info you need is on pages 92 and 93.

The drawing on p92 appears to be what you have based your design on including the high voltage circuit.

Section 7.3.1 gives you all the required details including the fact that it needs to be a POR to initiate monitor mode. The voltage on the circuit must drop to almost zero as well!

It seems you are making a USB2 version of the OSBDM/TBDML???

Good Luck!

Regards

Peg

[jjl3]

Mr Peg

you are right, these two connectors on my board, one is for USB, another is for Mon08.

I tried to reduce the voltage of Vtst, but result is same.

if I switch IRQ to VCC_CPU side, the crystal work well, RST is high, after power on.

but I can't make sure the JW32 working,

because I programed a wrong user program into JW32 the first time which I can enter monitor mode.

I have not ways to tell whether JW32 works.

if I switch IRQ to 8.2V side, the crystal stop at once, but RST is still high, under the already power on case.

it seems that 8.2v prohibit JW32 work.

Mr Alban,

whether the blank JW32 will force entering monitor mode, when power on?

it is necessary to connect Vtst for entering monitor mode under this case?

thanks for your reply!

best rgards

jjl

[Alban]

Hello jjl !

In case of a blank device, the voltage on IRQ is not important.

You do not need Vtst to enter MON08 with a blank device.

As peg mentioned, check that Vdd is going lower than 100mV when the Power On Reset is done.

Alban.

[jjl3]

Mr Alban

I had ever entered the monitor mode to program MCU successfully,

but after that, I had not entered monitor mode again.

I am very puzzled why MCU doesn't work when connect IRQ to Vtst?

perhaps 8.2V is much too high, I am trying with reducing Vtst into range 7.5V to 8V.

if have result, I will post again.

Thanks!

[peg]

Hi jjl3,

I use the voltage straight out of the MAX232 etc to power IRQ for monitor entry on a JB8 and a JB16 with no problems. I just measured it and its 9.4 volts!

So I don't think this is your problem.

One thing I don't like about your design is the toggle switch to select different xtals.

I don't know the JW specifically but I guess you use one for USB and one for MON08???

Usually you want the xtal VERY close to the chip.

One way to do this is put the normal xtal close to the chip then use a "canned" oscillator to override this for MON08. Just put a jumper in there to connect the output of the oscillator when required.

Just a few thoughts

Regards

Peg

[jjl3]

Thanks Mr Geezer and Alban!

this schematic for your reference.