
VIPER Technical Manual | Detailed hardware description |
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To write to OUT[0:7], write to the following PXA255 processor GPIO lines to drive the outputs.
VIPER outputs | PXA255 GPIO |
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OUT0 | GPIO20 |
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OUT1 | GPIO21 |
| PXA255 | GPIO[20:27] |
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| OUT[0:7] |
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| Transceiver |
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OUT2 | GPIO22 |
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| OUT0B | PL9 | ||
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OUT3 | GPIO23 |
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OUT4 GPIO24
OUT5 GPIO25
OUT6 GPIO26
OUT7 GPIO27
The PXA255 GPIO lines must be configured using the registers built into the device to ensure they function correctly. RedBoot configures GPIO20 – GPIO27 as outputs, and sets OUT0 to logic ‘0’, and OUT1 – 7 as logic ‘1’. Eboot cannot set these up as outputs as it only boots the Windows CE image. Once Windows CE is booted you can simply write to a mapped address. For an example of how to do this under Windows CE please see the Windows CE Technical Manual.
Please note:
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The GPIO lines are programmed using the GPCR0 and the GPSR0 to set the line to ‘0’ or ‘1’ respectively. The registers are
GPLR0 0x40E00000
GPSR0 0x40E00018
GPCR0 0x40E00024
© 2007 Eurotech Ltd Issue E | 58 |