MAC7200 datasheet(844/976 Pages) FREESCALE

844 / 976 page

Functional Description

MAC7200 Microcontroller Family Reference Manual, Rev. 2

766

Freescale Semiconductor

33.11.5.1 Command Queue

Each command work must go through the three stages of the command queue:

1. ATDCW: Stores a new command word

2. ATDCC: Stores the command word for the conversion currently executed

3. ATDRR: Stores the result of a conversion which has been executed already.

A command word must be written to the new command word register (ATDCW). From there it is pushed

further to the current command word register (ATDCC). A command word is pushed to ATDCC when a

previous conversion finished. If there was no previous conversion the command word is immediately

pushed to ATDCC after it was written to ATDCW.

The ATD conversion state machine (CSM) will execute the current command. Once the result of this

conversion has been determined the result (including parts of the current command word) is pushed to the

result register (ATDRR):

Figure 33-16. ATD Command Queue / Result Register

When the content of the ATDCW is pushed to ATDCC, there is again space for a new command word.

This makes it possible to have one command word being executed while fetching a new command word.

Both, MCU and the DMA, have access to the ATDCW register. The current command word can neither

be accessed via the MCU nor via the DMA. Only the conversion state machine is influenced by the current

command word.

When a conversion finished the result register (ATDRR[31:16]) is updated with the bits ATDCC[31:16]

(which have been the bits ATDCW[31:16] before) and the conversion result which is saved in

ATDRR[15:0]. The MCU or the DMA can read the result register.

33.11.5.2 Command Processing and DMA Requests

When enabling the ATD a command word will automatically be requested. After receiving the first

command word the ATD will start converting. The CWCM bits of the command word will tell the ATD

how to perform the conversion and what action to take after the conversion has completed:

ATDCW

New

command

word

Current

command

word

ATDRR

Result

Conversion

MCU

DMA

CSM

ATDCC

ATDCC is

empty

Conversion

finished

result

MAC7200 Datasheet(PDF) 844 Page - Freescale Semiconductor, Inc

MAC7200 Datasheet(HTML) 844 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL