topic Re: HC908GP32 Monitor Mode in 8-bit Microcontrollers

HC908GP32 Monitor Mode

xena — Sat, 24 Feb 2007 01:31:01 GMT

Hello.

I have a problem causing a POR to the HC908GP32.

I'm using this schema for programming the uC : http://www.hc08.net/projects/hc08pgmr_schematic.gif

Also,all the connections regarding entering Monitor Mode are followed as in datasheet(pag130 of original datasheet).

Even when i completely disconnect Vdd from the uC,on this pin there is aprox. 2.5V.From where,i don't know.

If somebody could answer to my following questions,i'll apreciate alot:

1.When i "give" a POR to this uC,the RST line and all other lines which are used to configure the uC for entering MON must be keped to the coresponding logical level?

2.Do you have other scheme for a GP32 programmer?

TNX.

Re: HC908GP32 Monitor Mode

bigmac — Sat, 24 Feb 2007 08:48:40 GMT

Hello,

Your schematic does not show how you have connected the programmer to the MCU - where does each pin on JP2 connect, since it does not appear to be a "standard" MON08 configuration.

"Even when i completely disconnect Vdd from the uC,on this pin there is aprox. 2.5V.From where,i don't know."

What is the pin that you refer to here? How are you applying power to the MCU, and how are you attempting to do a POR? You will also need to remove power from the programmer, as well as the MCU

Regards,

Mac

Re: HC908GP32 Monitor Mode

xena — Sat, 24 Feb 2007 08:54:14 GMT

I'm using a simple switch to do a POR on the GP32 uC.Is it wrong?If it is,can you tell me how should i do it? Also,can you give some valid refenteces about a programmer scheme which works?

tnx

Re: HC908GP32 Monitor Mode

xena — Sat, 24 Feb 2007 08:58:18 GMT

I forgot to mention that i built the programmer from the application note from freescale regarding HC908GP32 Monitor Mode. And it doesn't work at all.

Re: HC908GP32 Monitor Mode

bigmac — Sat, 24 Feb 2007 09:33:18 GMT

Hello,

I notice that, of the seven pins associated with JP2, none is a ground connection. If JP2 is the only connection with the target, and separate power supplies are used for programmer and target, and these power supplies are isolated, there will be a problem. There must always be a direct ground connection between the programmer and the target.

For a POR to occur, the Vdd voltage must drop below 0.1 volts. It is possible that this does not occur because you have a number of pull-up resistors (to 5V) in the programmer, that are connected pins on the MCU. The current flow into these pins, when Vdd is removed, can cause Vdd to remain above 0.1 volts, and POR will not occur.

The power to the programmer needs to be switched at the same time as the power to the target. Alternatively, you could supply power to the target, via the programmer, and then only the programmer needs to be switched. However, to do it this way will require more than seven connections to the target.

Regards,

Mac

Re: HC908GP32 Monitor Mode

xena — Sat, 24 Feb 2007 10:16:04 GMT

Thank you for these answers,Mac.

As i said above,i also built the programmer from the original datasheet of the gp32(page 130) with small modifications at the rs232 driver and using a 9.xxxMHz oscilator.Power for the MCU it is given from the programmer.

How can i have a POR for the uC in these conditions? Does the RST line of the uC have anything to do with de Monitor Mode(i ask this because in an electrical scheme the RST line of the uC was connected to the DTR pin from RS232).

Re: HC908GP32 Monitor Mode

peg — Sat, 24 Feb 2007 15:34:57 GMT

Hi xena,

If you look at the table in the Monitor ROM section of the data sheet that shows you the signal requirements for monitor mode entry, you will see that RST has little to do with it.

The DTR control of RST is a luxury that under certain circumstances provides a small benefit.

The Monitor Mode Circuit presented in the datasheet DOES work!

There is a thoasand different designs for monitor mode adapters but in the end they all do the same thing as the monitor mode requirements are quite strict and there is no possibility to modify the way that it works.

I think your problem is as Mac has said, you need to remove all power, a stray powered pullup will attempt to power up the whole chip when the main power is removed (well it certainly won't let it drop to the required 100mV or so)

Re: HC908GP32 Monitor Mode

xena — Mon, 26 Feb 2007 04:25:46 GMT

Thank you all for your answers. I will try again the scheme from the original datasheet of the GP32.I hope it will work

tnx

Re: HC908GP32 Monitor Mode

vs02rjn — Tue, 27 Feb 2007 04:14:48 GMT

Hello!
Is there any way in witch I can determine if the MCU has entered Monitor Mode? Because I have a hard time getting started with these MCUs as I have built a programmer after AN2317 (page 10) and I can't make it work. I have used ICS08 software from P&E Micro and all I get is hardware loopback. I have checked over and over again the connections and everything looks OK!
Please help!