see remarks inline

eric mcnamara wrote:
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hi all

as mentioned in a previous post, i am doing a project involving a 89c55wd mpu (8051 family) and a dallas ds17887 real time clock.

i am hooking the mpu up to a 20 x 2 lcd display

can i use the port 0 drivers for the rtc , ie: ad0-ad7 on mpu to ad0-ad7 on rtc


and likewise use port 2 drivers for driving the lcd, ie: a8-a15 on mpu to db0-db7 on lcd display.

Why would you connect address lines to data lines?
I'd suggest you use a 8052 port to send the data. See the links section and search google and this site for " hitachi lcd 44780". It is very likely, but not sure, that your display would 44780-compatible... You would probably want to use the display in 4bit mode as you will need 2 ports (p0 and p2) for address/data-bus to your rtc. ad0-ad7 from 8052 to rtc seems ok, but check the timing of adres/data/control signals and you will also need to decode ad8-ad15 in order to generate a CS signal to your rtc.

That's how I would start. Other people may have other (and better) idea's about this...


?

the lcd will have a built in lcd driver, so i can hook it directly to a mpu without too much hassle.

I suggest you start by writing up some firmware to sent something to the display. I have been able to empirically determine that this is not as straightforward as it seems :-)

the real time clock im not so sure,

i have firmware code for the mpu ready (for the rtc)

what firmware code? you have not yet been able to connect your rtc to your controller, so how can you be sure about your code?

thanks for all your help.

eric


ps: when i burn the mpu with the code, only to discover i need to make corrections, can i re-burn a new code????
If it's a OTP-device: no... You would anyhow be better of by using a development kit, so you can test your routines in RAM. There are some decent low-cost kits available, check google and 8052 web-ring


rgds
Patrick