HI-6136 Datasheet, PDF(116/206 Page) Holt Integrated Circuits

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HI-6136 Datasheet, PDF (116/206 Pages) Holt Integrated Circuits – 40 MHz SPI Host Interface

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HI-6136

Bit No.

4-0

Mnemonic

BUSID

WC4:0

Function

Bus Identification.

If this bit equals zero, message was transacted on Bus A. If bit equals one, it was trans-

acted on Bus B.

Word Count.

This 5-bit field contains the word count extracted from the command word. Zero indicates

32 words.

15.2. Mode Command Message Information Words

Mode command data structures in shared RAM are similar to those for subaddresses. Mode codes 0 through 15

(0x0F) do not have an associated data word, so data structures for these mode code values have just a Message

Information Word and Time-Tag Word. The Message Information Word is stored at the memory address specified by

the descriptor table Data Pointer. Mode codes 16 through 31 (0x10 through 0x1F) have one associated data word.

The Message Information Word is stored at the memory address specified by the descriptor table Data Pointer, and

the Time-Tag Word is stored in the following location. The data word is stored at the memory address specified by the

Data Pointer plus two locations.

15.2.1. Receive Mode Command

The receive mode command data structure contains a Message Information Word, a Time-Tag Word and may con-

tain one Data Word. If a receive mode command has a data word, the device may apply the data as defined by MIL-

STD-1553, plus store the received single mode data word at the address specified by the Data Pointer, plus two

locations. Refer to the Mode Code Command Summary in Table 10.

Here is an example data structure for a receive mode command with data (mode code values 0x10 through 0x1F).

Notice that the Data Pointer points to the data structure starting address, not the mode data word. The data pointer is

located in the receive mode commandâs Descriptor Block, fully described later:

Data Buffer

Hex Address

Word Description

Word is Written By ...

Data pointer equals 0x1500 â 0x1500

0x1501

0x1502

Message Information Word Device, after message completion

Time-Tag Word

ââ

Mode Data Word

ââ

Three receive mode commands with data are not defined under MIL-STD-1553B. These are MC16, MC18 and MC19

(mode codes 0x10, 0x12 and 0x13 respectively). However the device responds âin formâ if illegal command detection

is not used (corresponding bits in Illegalization Table are logic 0) and the UMCINV bit in the âRemote Terminal

Configuration Register (0x0017)â is logic 0.

For mode code commands without data, the data structure contains only the Message Information Word and Time-Tag

Word.

Here is an example data structure for a receive mode command without data (mode code values 0x00 through 0x0F).

Note: None of these receive mode commands are defined under MIL-STD-1553B but the device responds âin formâ if

illegal command detection is not used (corresponding bits in Illegalization Table are logic 0) and the UMCINV bit in the

âRemote Terminal Configuration Register (0x0017)â is logic 0. Notice that the data pointer points to the data structure

starting address, the message information word. The data pointer is located in the receive mode commandâs Descrip-

tor Block, fully described later:

HOLT INTEGRATED CIRCUITS

116

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