Quatech, Inc. | Airborne Enterprise Module Databook |
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the Airborne Device Server module by the host at the same time the Rx message header is sent to the host from the Airborne Device Server.
The Tx message header consists of a Command (CMD) byte, followed by three Parameter (PARM) bytes. They are described in the SPI Commands section (7.4) below.
The Rx message header consists of a Rx Data Available field, and a Tx Buffer Available field. The Rx Data Available field indicates the number of data bytes the Device Server has available for the host. They can be received by the RXDATA command. The Tx Buffer Available field indicates how many data bytes the Device Server is able to accept from the host. This data is to be shifted in by the host using the TXDATA (Table 16) command. Both fields are 16 bit values and are stored in
Table 14 - Tx Message Header
0
1
2
3
CMD
PARAM1
PARAM2
Table 15 - Rx Message Header
0
1
2
3
Rx Data Available
Tx Buffer Available
7.4SPI Commands
The following commands are available for use in the CMD message header.
Table 16 - SPI Command Description
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| Description |
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| (Hex) |
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| 0x00 |
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| NOP |
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| The NOP command does nothing. | |
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| It is intended to be used when the host wants to simply retrieve | |
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| the Rx Message Header without any other operation. | |
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| 0x04 |
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| BREAK |
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| The BREAK command will issue a break sequence to the | |
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| module. | |
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| It is analogous to the BREAK signal on a common UART. | |
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| 0x08 |
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| TXINTCLR |
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| The TXINTCLR command will clear the Tx interrupt. | |
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| Use this command when the module is issuing a Tx interrupt but | |
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| there is no more data to send. This is analogous to the reset Tx | |
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| interrupt command on a common UART. | |
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24 | 8/11/2009 |