Re: Help needed for microcontroller based project.

On 7 Jan 2006 07:29:10 -0800, the renowned "adam"
<adam.mashraqui@xxxxxxxxx> wrote:

>Hi Group,
>We are a group of four B.E students studying in M.h.S.S. COE, Mumbai,
>India. We writing to you to seek some help and guidance. Since this is
>our first microcontroller based project, we are unaware about the
>practicalities and methodologies that go into it.
>In our project, we have decided to use the following:
>AT89C52/AT89S52: MICROCONTROLLER
>DS1307: RTC
>MAX232/MAX485: LEVEL CONVERTER
>AT24C1024: SERIAL EEPROM
>4051B: 8:1 ANALOG MUX
>IC 741/ LM324: COMPARATOR
>
>LOGIC: 8 channels connected to the MUX, depending on which input is
>enables, MUX selects it and sends it to the COMPARATOR. The second
>input to comparator is a reference voltage. Comparator's output to port
>1.0. Ports 1.1,1.2,1.3 as selects lines to MUX. Ports 1.4,1.5 for
>intefacing with memory. Ports 3.0,3.1 as RXD and TXD. Ports 3.2,3.3,3.4
>for interfacing with RTC.
>Using select lines of MUX , we wish to determine which channel is
>enabled.
>using RTC we wish to sore the real time and pin number in EEPROM. Using
>RS232C we wish to display this data on a PC.
>
>We are facing the following queries:
>1. Is our logic correct? Are all the Ic's comaptible?
>2. Useful tips from your side.

Sounds okay.

Suggest you use an LM339 rather than an LM324 or 741 (the latter would
require a negative supply to get common mode range that includes
ground and you'd then have to clamp the output to the rails to avoid
problems with the micro. The 339 just requires a pullup resistor (or
maybe not even that if you use a pseudo-bidirectional input).

Get something very simple like the I2C + RTC + serial communications
working first (say transmitting the current time to a PC one-way) and
then build on that.

You can write this in assembly or C (or C++ but that would not make
much sense). See what software your school has licenced for your use--
compilers and PCB CAD packages are generally not free.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@xxxxxxxxxxxx Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
.

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