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vk4tec

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Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 03:29pm 27 Apr 2012

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Hello

I wonder if anytone has used a MAX7219 based LED display ?

It appears to have CLK LOAD DIN

The datasheet says it uses SPI - can the DuinoMite do SPI ?

Looks like a 16 bit number is to be clocked in.

Looks like LOAD is then set.

DIN data is loaded 16 bits on clk rising edge.

This one is 7-segment 8 digit

LOAD must be LOW to clock data into the chip.

The 16 bit number consists of

D15 - D12 ( not used )
D11 - D08 ( Address )
D07 - D00 ( Data MSB - LSB )

Seems quite simple

Need to send 16 bit numbers using clock, then set LOAD to HIGH

INIT

0A08 - Set Intensity middle
0B07 - Scan Limit ( 8 digits )
0900 - No decode BCD
0C01 - No shutdown
0F00 - No display test

Send each DIGIT 1,2,3,4,5,6,7,8

0000 0001 0000 0001 ( Address = 1, data = 1 )
0000 0010 0000 0010 ( Address = 2, data = 2 )
0000 0011 0000 0011 ( Address = 1, data = 3 )
etc

10 MHz serial interface

- Andrew - Edited by vk4tec 2012-04-29

Andrew Rich VK4TEC
www.tech-software.net

vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 05:02pm 27 Apr 2012

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Is there any issues with the PIC32 only being able to drive 3.3 Volts on the SPI ?

Some devices might need above 3.3 VOLTS ?

- Andrew -

Andrew Rich VK4TEC
www.tech-software.net

JohnS
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Joined: 18/11/2011
Location: United Kingdom
Posts: 4020

Posted: 05:18pm 27 Apr 2012

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The target (slave) device data sheet should detail its voltage needs. If its supply voltage is up to about 3.6V all should be OK. If it's a 5V device, you could be needing level shifters.

John

vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 05:30pm 27 Apr 2012

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Am I barking up the wrong tree here ?

Is SPI ONLY available on UEXT on a DuinoMite MINI ?

I am trying to assign SPI to the 26 way connector

Because MOD-GPS is already on the UEXT

- Andrew -

Andrew Rich VK4TEC
www.tech-software.net

vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 06:04pm 27 Apr 2012

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Fixed

I have SPI on 26 way connector

SETPIN 16,2 RX
SETPIN 17,8 TX
SETPIN 18,8 CLK ( Low Speed = L)

do
a = SPI(16,17,18,&HAA,L)
loop

Andrew Rich VK4TEC
www.tech-software.net

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