89V51RD2

[Jan Waclawek]

Again, it depends on the _combination_ of crystal frequency and baudrate (and, slightly, also on the RS232 convertor you use).
And there is always a tolerable error in the setting of the baudrate, say 3% or so.
You can try to set your crystal frequency to the excel sheet at the link I gave and you will see...

For 16MHz, at 9600, you should be on the safe side.

Jan Waclawek

[Zeesha]

Hi,

As advised by you, i tried the baud rate setting of 9600 at a 16Mhz crystal. i am using a 232 convertor of intersil 3221.

I am unable to Flash my code, and get a message of "unable to connect at the specified baud rate. Try reducing the baud rate and connect again" .
I have tried all possible baud rates..

Can u please tell me the possible problem ..

Hoping for an early reply

Thanks,

[erikm]

Try disable auto-powerdown on the 3221.  Many have had problems with that.

Erik

[Jan Waclawek]

I just tried the 16MHz crystal and the autobaud works well up to 28800 (the 3.5% error is probably acceptable if small pulse distortion is present - short cable). At 38400 bauds it was unreliable, kicking in perhaps once in 5 attempts - the xls table predicted 1 out of 3 but this really does not matter here.

So you need to go down checking the usual things - get a terminal program, set 9600, press and hold "U" and reset the controller. If it does not start echoing "U"s, check the UART using a loopback connector. If OK, check the cable placing the loopback at its end. Then connect to your board and short together Tx and Rx pin at the controller - this should make no harm and you should see the echo (if the controller is socketed, you can take it out if you don't feel comfortably shorting pins together...).  If the whole datapath is OK, it's time to check the circuit - check power supply directly at the controller's pins, check RESET, check if the oscillator is running (and oscillating at 16MHz...). As a last option, try an another controller - the bootloader can be damaged, and/or missing; and/or the controller itself can be damaged.

Hope some of these will help.

Jan Waclawek

PS. Ufff, I just see Erik's answer, he probably hit it....



Post Edited (03-31-05 05:31)

[Raghu]

I am using Flash Magic V2.07.

Using it to program P89v51rd2.

The tick marks for Set Security Bit 1 and 6 Clks/ cycle always come ticked ON. And  when I try to program leaving them that way I get the warning dialog boxes.

I know the tick marks reflect the status of both options.

 But how to  get out of this  nuisance of clearing both tick marks everytime I program ? ( I don't want to set any security bit and leave the 6 clock as it is )

Thanks for any pointers.

Raghu

[Andy Ayre]

Doesn't a full device erase clear the security bit? It should, and afterward you should uncheck it. It should then remain unchecked. Let me know.

[Raghu]

I did in fact try out a full flash erase. But still the security bit remains set.

Most probably there is some issue with the MCU as a full erase is completed within a second - just click the option and it immediatley says " Erase Complete " . Reason why I think that there is some problem with the MCU.

I shall check out with another MCU and revert.

Thanks for responding.

Regards

Raghu

[Selva]

Hello All!!!!!!!!!
           Can anybody suggest me how I can get baud rate of 38400 using 89C51RD2 and 22.1184(or 18.432)MHz?  Because I am unable to achieve this baudrate using 89C51RD2HBP and the above two crystals.......

Selva

[erikm]

Can anybody suggest me how I can get baud rate of 38400 using 89C51RD2 and 22.1184(or 18.432)MHz? Because I am unable to achieve this baudrate using 89C51RD2HBP and the above two crystals.......



keil baudrate calculator
http://www.keil.com/c51/baudrate.asp

Will show you that you need to use T2 with the 18.432 and T2 or SMOD=1 for the 22.1184.

DO note that you can not use 6 clock mode with the 22.1184 xrtal.

Erik

[erikm]

oops, sorry

This should not have been answered in this forum

Erik

[nitin]

               
 

             sir,
                  we are doing serial programing of 89c51rd2bn, but it is not working. with use of 89c51rd2hbp itis possible. plz give us solution.
                                                                                thank you
                                                                                nitin

[Andy Ayre]

Please post a detailed description of the problem, so we know what to start checking. Thanks.

[Sud]

I want to know if 89c51rd2 can be directly replaced by 89v51rd2 without any changes (hardware or software)?
Else please list out the differences.

[Andy Ayre]

There are two kinds of RD2, there is the P89C51RD2Hxx and the P89C51RD2xx. The best way to find the differences is to compare the datasheets of the two devices.

[Sud]

Hi Andy,
I know about the "P89C51RD2Hxx" & the "P89C51RD2xx" versions. What I asked was the difference between "89C51rd2" & "89V51rd2". Can I replace the "C" version with "V" version without any software or hardware changes?
I will refer the datasheet but it would help if somebody can share his experience.
Sud.