Author Topic: Hardware ISP for Flash magic?  (Read 19990 times)

sandeep

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Re: Hardware ISP for Flash magic?
« Reply #15 on: February 09, 2005, 09:22:04 am »
another query is that do we need to use the circuit in the BOX for 89C51RD2BN chip ??

erikm

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Re: Hardware ISP for Flash magic?
« Reply #16 on: February 09, 2005, 12:57:11 pm »
i have a problem andrew....the circuit in AN461 shows two squares at pins 7 and 9 of MAX232, and another square at the location below the microcontroller where the NORMAL and ISP switch has been shown. What do these squares mean ??
Nothing yes NOTHING connected here

another query is that do we need to use the circuit in the BOX for 89C51RD2BN chip ??

you can forget the 5V to 12V circuit unless you need very high speed programming.  Just connect Vpp to +5V

Erik

Arch Yap

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Re: Hardware ISP for Flash magic?
« Reply #17 on: February 17, 2005, 11:45:56 pm »
i'v faced the similiar problems with 89C51RB2, and i've follow the same instruction as belows;-

a)  PSEN held low with R 2k Ohm
b)  P2.6 or P2.7 are high or floating
c)  ALE is high or floating

and i've check the signal from scope, and the char "U" is seen at the RXD of the MCU, but not signal is out from TXD signal.  

i'm need your help to overcome this or any reference circuit that i can refer ??? TQ

Erik, Pls e-mail me if you do !!

erikm

  • Guest
Re: Hardware ISP for Flash magic?
« Reply #18 on: February 18, 2005, 05:00:27 am »
>>i'm need your help to overcome this or any reference circuit that i can refer ??? TQ

Erik, Pls e-mail me if you do !!<<

Why should I e-mail you and keep the answer secret from other participants in this forum?

My guess is that you have lost the reset vector by using RC reset.
The only remedy there is parallel programming.

Install NoTouch (and "the backdoor") in factory fresh chips and with every bupdate and this will never happen again.

Erik