Interfacing CD4052 with 2 uarts in 8051

As you know, the processor has a limited number of registers. Even if you combine all register banks, it's not enough for a full $GPRMC string.

So you then have two options - already covered earlier in this thread:
- process the data one byte at a time directly when receiving the characters. Store state machine state and decoded field data in variables.
- store a full line of text in a character array. Then decode it.

Decoding of the data is done almost identically whatevery processor or computer language you are using.

Note that NMEA is a protocol standard. But that doesn't mean that you can't find GPS modules that supports or uses other protocols. And not all GPS modules supports all NMEA strings. More importantly - different modules emits different sets of NMEA strings default when powered up - you may need to send an init string to the module to change the set of NMEA strings it should emit - and what frequency the GPS should use for the individual strings. That means that you need the manual for the selected GPS. Don't ever get a GPS without already having access to a good manual. The same, obviously, goes for the GSM module - you may need to use manufacturer-specific AT commands. And their existence requires you to have the AT protocol documentation.

As you know, the processor has a limited number of registers. Even if you combine all register banks, it's not enough for a full $GPRMC string.

So you then have two options - already covered earlier in this thread:
- process the data one byte at a time directly when receiving the characters. Store state machine state and decoded field data in variables.
- store a full line of text in a character array. Then decode it.

Decoding of the data is done almost identically whatevery processor or computer language you are using.

Note that NMEA is a protocol standard. But that doesn't mean that you can't find GPS modules that supports or uses other protocols. And not all GPS modules supports all NMEA strings. More importantly - different modules emits different sets of NMEA strings default when powered up - you may need to send an init string to the module to change the set of NMEA strings it should emit - and what frequency the GPS should use for the individual strings. That means that you need the manual for the selected GPS. Don't ever get a GPS without already having access to a good manual. The same, obviously, goes for the GSM module - you may need to use manufacturer-specific AT commands. And their existence requires you to have the AT protocol documentation.

Here what I got for the 20 Channel EM-406A SiRF III Receiver with Antenna GPS module.
Here is the link : www.sparkfun.com/.../product_info.php

What should I look in manual for selecting whether the GPS module is good or not.

FIRST get the serial going

do ONE thing at the time, do NOT jump all over the place

Erik

Remember: on an 8051, there is no such thing as just, "the memory".

The 8051 has several different memory areas - DATA, IDATA, XDATA, etc...

Why do you think this world has so many different GPS modules? Every customer has his own needs.

Only you know what parameters are important to you. That was why I did post a short list of parameters to think about. There are more parameters too:
- type of connection (surface-mounted, pin header, bluetooth, ...)
- price
- availability
- availability of good documentation
- temperature range (industrial, automotive, military, ...)
- civilian or military (max speed, height, jerk, ...)
- fully intelligent GPS or using your processor for the computations.
- support for real-time GPS correction.
...

The list can be made almost infinitely long.

You must make the requirements list.

You must give different requirements different weights.

You must figure out which GPS gets best score.

My "best" GPS is not your "best" GPS.

For a school project, it's enough that it uses supply and signalling voltages you are able to interface, a connector you are able to interface to, and the ability to detect satellites in the environment you are going to demonstrate the design in. All else are just optional extras. If you have special goals with your project, then you obviously have to bring in more parameters when scoring the GPS - we don't know what these parameters may be because we don't know your goal.

There are more parameters too

and a very important one if you plan to use it downtown

dead reckoning

downtown you will be lost without it

Erik

I'm basically planning to write C program and in some parts combining with the assembly too.
i.e 1)Inputting the data and processing it(Byte manipulation)i think i would do in C eg String comparison by strncmp(). u would have got an idea.

2) Bit manipulation such as SETB PSW.3 CLR PSW.3
I Intend to do by Assembly, Creating delays (since assembly provides exact delays using Timers)

Hence my program would be a combination of C and Assembly

Yes, it's good to use both 'C' and assembler for their particula advantages - but the 2 examples you gave don't actually require assembler!

"2) Bit manipulation such as SETB PSW.3 CLR PSW.3"

There is no need for assembler there - Keil C51 can do that perfectly well.

See: http://www.keil.com/support/man/docs/c51/c51_extensions.htm

"assembly provides exact delays using Timers"

Assembly has no particular advantage when using the hardware Timers - because it's the hardware that controls the timing, not the software.

It's when you're trying to do software delay loops that you need assembler...

See: www.8052.com/.../162556

(note that software delays are not generally a great idea)

Yes, that'd be an appropriate place to use 'C'.

But note that writing in any High-Level Language (HLL) means (among other things) that you delegate use & control of the CPU registers to the compiler.

So this answers your earlier question about using registers or "memory" (sic) for your data...

I usually do my projects(or would say have done my projects)in ASM.I would be doing embedded C for the first time. I went through all the examples from Mazidi.Now I can even write my programs in C(In fact it makes work lot easier).
But when it comes to wwriting C and assembly together I'm stuck. I went through the tutorial at :www.8051projects.net/.../mix-c-and-assembly.php

I wasnt able to understand a thing.
Can u all post a link from where I can learn mixing C and assembly.Or any book u can suggest.Regarding books I've downloaded " Embedded C :Michael J. Pont"
Pls help