Communication between 2 processors

ertansuluagac · Joined: 13 Jul 2017 Posts: 135 Location: IZMIR

I want to have 2 processors talk among themselves. Is serial communication a good method? or is there a method you can suggest?
Used processors:
18f45k22
18f67k40
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Es

temtronic · Posted: Thu Nov 28, 2019 6:28 am

It depends upon how much data has to be sent to them,how often and distance. Obviously parallel is faster( bytes or nibbles vs bits) but serial may be easier for you , especially for testing. You can 'sniff' the data with a PC and terminal program. Distance ? if less than 10 feet use parallel for speed.

Jay

ertansuluagac · Joined: 13 Jul 2017 Posts: 135 Location: IZMIR

There is no distance anyway. They will be on the same card. I'm using the first processor to drive the screen. And I use the data from the second processor to press the screen.

2. The processor will send the data generated to the 1st processor. So:

1. Processor 2. Processor
RX ---------> TX
TX <------- RX
it will be.
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Es

temtronic · Posted: Thu Nov 28, 2019 7:08 am

Assuming an LCD 'screen', use serial as it takes longer to display data on LCD than actual data transfers, so no benefit from using parallel methods.

Jay

ertansuluagac · Joined: 13 Jul 2017 Posts: 135 Location: IZMIR

I think there is no need for max232 between the two processors. Or do have?
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Es

Ttelmah · Joined: 11 Mar 2010 Posts: 19550

None whatsoever. Just direct wire. Choose a baud rate dependant on how
long the connection is. If only a few inched 500000bps for example. If
longer bring this down. Remember if you do use a fast rate you must
use interrupt driven receive.

ertansuluagac · Joined: 13 Jul 2017 Posts: 135 Location: IZMIR

near. They will even be on the same card. 1. The processor is constantly sending data.
I'm using the second processor to drive 320x240 graphics lcd. and, I print data values from the first processor.

alan · Joined: 12 Nov 2012 Posts: 357 Location: South Africa

Wht not use SPI if you have spare pin. Comms are then synchronous if that are needed.

Ttelmah · Joined: 11 Mar 2010 Posts: 19550

A question here is what the chips use for clocks?.
If the two chips both have crystals, or share an external master oscillator,
or both have oscillators that are guaranteed to remain within a small
percentage of one another, then really SPI has no advantage. Simple
async, is easier to code and uses less wires. Where SPI 'wins' is if the
clock cannot be guaranteed to be this close. It also does give a fractionally
higher throughput for a given baud rate (1.25*), by not requiring start
or stop bits.