# DS89C440 Programmer Problems

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#### yolan

##### Newbie level 5
mtk 89c450

I'm trying to build the in-system programmer for the DS89C440 with the schematic that can be found in the application notes on Maxim's site (https://www.maxim.de/appnotes.cfm/appnote_number/3262). The problem is that once I get the circuit built, the programmer won't detect the microcontroller. I am using maxim's MTK. Once I have the MTK open the serial port, I get some gibberish from the microcontroller, but when I run the loader, I get an error saying that the loader cannot connect to the device. I've looked over the circuit a few times and it seems like I have everything connected correctly. In hyperterminal, you recieve gibberish and you can type things and it seems like it is sent over the serial line.

I'm using a MAX233A instead of the MAX232 in the schematic.

Any ideas would be appreciated.

#### IanP

##### Advanced Member level 5
max 233a ds89c450

If you have proper baud rate, and for 11,0592MHz, for example, the baud rate is 14,400bps, you shouldn't have "gibberish", or whatever you mean by that, but ASCII characters ..

Using MTK try the following sequence:
- Open COM port,
- Reset microcontroller (power ON),
- Connect to loader,
- Reset microcontroller again (power OFF and ON),
- Connect to loader again ..

Regards,
IanP

#### yolan

##### Newbie level 5
programmer problems

Ok I'll give that a try. The gibberish as I called it is just a bunch of ASCII characters.

I am using an 11,0592MHz clock.

Added after 3 hours 25 minutes:

Ok, I tried the boot sequence above at 14400bps with no success. I don't even get random ASCII characters at 14400. If I set the speed down to 1200 I get the ASCII again. When I do a connect to that I get:

Code:
Did not receive R prompt
Unable to establish communication with target.
Check connection to target system or consult help files.

#### IanP

##### Advanced Member level 5
89c450 programmer mtk

With 11,0592 crystal connection should be establshed at 14,400 or 19,200 ..
This error message of yours may indicate that the RS-232 path is not in order ..
Could you remove DS89C440 and shorten pins 10 and 11 in the mpty socket; then, with the power ON, run Hyperterminal, or any other terminal software, and type characters from the keybard: on the computer screen you should see ECHO of the typed characters ..
Once you are sure that the RS-232 loop works, place the DS89C440 back in its socket, in the MTK configure the COM port to 14,400, open COM port and Connect to Loader .. and turn power to the DS89CXXX .. and you should see the following:
Code:
<0D><0A>
<0D><0A>

DS89C450 LOADER VERSION 2.1  COPYRIGHT (C) 2002 DALLAS SEMICONDUCTOR<0D><0A>
> 89C450 LOADER VERSION 2.1  COPYRIGHT (C) 2002 DALLAS SEMICONDUCTOR
> R<0D><0A>
R<0D><0A>
LB:00 OCR:FF ACON:1F CKCON:01 P0:FF P1:FF P2:FF P3:FF FCNTL:B1<0D><0A>
>W  CKCON 1<0D><0A>
W CKCON 1<0D><0A>
<0D><0A>
> W  ACON 00<0D><0A>
W ACON 00<0D><0A>
<0D><0A>
> <0D><0A>
<0D><0A>
>

Regards,
IanP

#### yolan

##### Newbie level 5
ds89c440 programmer

I tried hooking the two pins together. When no battery is hooked up, hyperterminal just echoed anything I entered. After I hooked the battery up to the project, hyperterminal still echoed the output, but every once in a while when I typed something a random ascii character was returned instead of the one I typed. So does that mean I may have a loose connection at my RS233, or maybe a bad RS233?

#### IanP

##### Advanced Member level 5
First of all, make sure that you have firm +5V at pin7 of the MAX233 ..
At this supply voltage MAX233 will provide an RS232 voltage swing from roughly -10V to +10V ..

Secondly, looking at the diagram below, connect R1in with T1out ..
Now, apply 0V to T1in (equivalent to TTL LOW at microcontroller TX pin); you should read 0V at R1out .. If you apply 5V (TTL High) to T1in, you should read TTL High at R1out .. and so on ..
In the same time you should read +10V at pin T1out (0V -->T1in) or -10V at T1out (5V -->T1in) ..

You have to sort it out ..
Without working RS232 path there is no point of testing DS89C440 ..

Regards,
IanP

### yolan

Points: 2
Helpful Answer Positive Rating

#### yolan

##### Newbie level 5
Sorry it's been a while, had a test to prepare for.

Ok, so I've checked the max233 now. When testing the max233 with the TX and RX pins connected to eachother, it echos in Hyperterminal. Also when in debug mode in the MTK I get:

Code:
<0D><0A>
<0D><0A>

R<0D><0A>
R<0D><0A>
Unable to establish communication with target.
Check connection to target system or consult help files.

When I hook the microcontroller back up I recieve:

Code:
<0D><0A>
<0D><0A>
<0D><0A>
<0D><0A>
<0D><0A>
Unable to establish communication with target.
Check connection to target system or consult help files.

Also on the MAX233, the voltages read
Pin 2: 5V
Pin 3: 5V
Pin 4: +10V
Pin 5: -2.3V
on the serial side and 5V on the 8051 side.

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