Subject:
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Re: Addresses of SPI ports
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 20 May 1998 08:05:39 GMT
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Original-From:
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Mark Limb <s003348@student.NOSPAMuq.edu.au>
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Viewed:
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2132 times
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Hi Arthur,
The SPI expansion header is shown below:
---------- Pinouts: 1 Gnd
| 2 | 1 | 2 Vcc 5V
| 4 | 3 | 3 SS*
| 6 | 5 | 4 MISO
| 8 | 7 | 5 SCK
---------- 6 MOSI
7 & 8 Not connected
I assume you will be using the Handy Board as a MASTER device not a SLAVE so
the following information relates to the SPI MASTER mode.
Port D address is $1008
The SS* pin is connected to Port D5. It is active low and is used to activate
the external device, like a chip select pin.
The MISO pin is connected to Port D2. It is used to serially input data to
the SPI. This pin should be connected to the Data Out of the external device.
The SCK pin is connected to Port D4. It is used to clock the data from the
SPI data register into the external device via the MOSI pin. As data is
outputted it is simultaneously inputted to the SPI data register from the
external device. So after one 8bit transfer the SPI data register will
contain the output from the external device. This pin should be connected to
the clock of the external device.
The MOSI pin is connected to Port D3. It is used to serially output data from
the SPI. This pin should be connected to the Data In of the external device.
You should set the DDRD ($1009) pins for I/O according to the function of the
SPI, ie the SCK (PD4) should be set for output using the DDRD.
The SPI control register ($1028) is used to set the configuration for the SPI,
bits are as follows:
7 SPI interrupt enable
6 SPI system enable (Must be set)
5 wired OR mode select, (Clear it, unless you know what it does)
4 Master/Slave select, (Set for MASTER Mode)
3 Clock polarity (clear for SCK low idle)
2 Clock phase select (clear for most devices)
1,0 Bit rate (clear both for maximum transfer rate, E clock/2)
SPI status register ($1029) just shows flags of the current SPI status
bits are as follows:
7 SPI transfer complete flag
6 Write collision error flag, (set only if SPDR is written during a data
transfer)
5 Not used
4 Mode fault error flag, (Set if SS* is sent low by external device)
3,2,1,0 Not Used
The Most important register is the SPI data register ($102A). This is where
you put your 8bit data block which you want sent through the SPI to the
external device.
After a transfer you can read this register to access the information sent
from the external device.
I hope this info has been helpful
Joshua Wherrett
Arthur Tretyak wrote:
> Hello. I was wondering if anyone knows all 4 addresses for all 4 ports of
> SPI header. Thank you
> --
> *************************************
> * Arthur Tretyak *
> * or just Arturchik *
> * a-tretyak@nwu.edu *
> *************************************
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