Motor de Búsqueda de Datasheet de Componentes Electrónicos
Selected language     Spanish  ▼

Delete All
ON OFF
ALLDATASHEET.ES

X  

Preview PDF Download HTML

AT91SAM7X256 Datasheet(PDF) 92 Page - ATMEL Corporation

No. de Pieza. AT91SAM7X256
Descripción  AT91 ARM Thumb-based Microcontrollers
Descarga  664 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Fabricante  ATMEL [ATMEL Corporation]
Página de inicio  http://www.atmel.com
Logo 

AT91SAM7X256 Datasheet(HTML) 92 Page - ATMEL Corporation

Zoom Inzoom in Zoom Outzoom out
 92 / 664 page
background image
92
6120D–ATARM–02-Feb-06
AT91SAM7X256/128 Preliminary
19.3.4
Abort Status
There are two reasons for an abort to occur:
• access to an undefined address
• an access to a misaligned address.
When an abort occurs, a signal is sent back to all the masters, regardless of which one has gen-
erated the access. However, only the ARM7TDMI can take an abort signal into account, and
only under the condition that it was generating an access. The Peripheral DMA Controller and
the EMAC do not handle the abort input signal. Note that the connections are not represented in
Figure 19-1.
To facilitate debug or for fault analysis by an operating system, the Memory Controller integrates
an Abort Status register set.
The full 32-bit wide abort address is saved in MC_AASR. Parameters of the access are saved in
MC_ASR and include:
• the size of the request (field ABTSZ)
• the type of the access, whether it is a data read or write, or a code fetch (field ABTTYP)
• whether the access is due to accessing an undefined address (bit UNDADD) or a misaligned
address (bit MISADD)
• the source of the access leading to the last abort (bits MST_EMAC, MST_PDC and
MST_ARM)
• whether or not an abort occurred for each master since the last read of the register (bits
SVMST_EMAC, SVMST_PDC and SVMST_ARM) unless this information is loaded in MST
bits
In the case of a Data Abort from the processor, the address of the data access is stored. This is
useful, as searching for which address generated the abort would require disassembling the
instructions and full knowledge of the processor context.
In the case of a Prefetch Abort, the address may have changed, as the prefetch abort is pipe-
lined in the ARM processor. The ARM processor takes the prefetch abort into account only if the
read instruction is executed and it is probable that several aborts have occurred during this time.
Thus, in this case, it is preferable to use the content of the Abort Link register of the ARM
processor.
19.3.5
Embedded Flash Controller
The Embedded Flash Controller is added to the Memory Controller and ensures the interface of
the flash block with the 32-bit internal bus. It allows an increase of performance in Thumb Mode
for Code Fetch with its system of 32-bit buffers. It also manages with the programming, erasing,
locking and unlocking sequences thanks to a full set of commands.
19.3.6
Misalignment Detector
The Memory Controller features a Misalignment Detector that checks the consistency of the
accesses.
For each access, regardless of the master, the size of the access and the bits 0 and 1 of the
address bus are checked. If the type of access is a word (32-bit) and the bits 0 and 1 are not 0,
or if the type of the access is a half-word (16-bit) and the bit 0 is not 0, an abort is returned to the
master and the access is cancelled. Note that the accesses of the ARM processor when it is
fetching instructions are not checked.
The misalignments are generally due to software bugs leading to wrong pointer handling. These
bugs are particularly difficult to detect in the debug phase.


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




Enlace URL




Privacy Policy
ALLDATASHEET.ES
Does ALLDATASHEET help your business so far?  [ DONATE ]  

Todo acerca de Alldatasheet   |   Publicidad   |   Contáctenos   |   Política de Privacidad   |   Favorito   |   Intercambio de Enlaces   |   Lista de Fabricantes
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn