AT91SAM7X128 Atmel, AT91SAM7X128 Datasheet - Page 509

• Manufacturer Part Number: AT91SAM7X128
• Description: MCU 32-Bit 91S ARM7TDMI RISC 128KB Flash 1.8V/3.3V 100-Pin LQFP
• Manufacturer: Atmel

Specifications of AT91SAM7X128

• Package: 100LQFP
• Device Core: ARM7TDMI
• Family Name: 91S
• Maximum Speed: 55 MHz
• Ram Size: 32 KB
• Program Memory Size: 128 KB
• Operating Supply Voltage: 1.8|3.3 V
• Data Bus Width: 32 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 62
• Interface Type: CAN/Ethernet/SPI/I2S/TWI/USART/USB
• On-chip Adc: 8-chx10-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 3

6120H–ATARM–17-Feb-09
Figure 36-3. Message Acceptance Procedure
If a mailbox is dedicated to receiving several messages (a family of messages) with different
IDs, the acceptance mask defined in the CAN_MAMx register must mask the variable part of the
ID family. Once a message is received, the application must decode the masked bits in the
CAN_MIDx. To speed up the decoding, masked bits are grouped in the family ID register
(CAN_MFIDx).
For example, if the following message IDs are handled by the same mailbox:
The CAN_MIDx and CAN_MAMx of Mailbox x must be initialized to the corresponding values:
If Mailbox x receives a message with ID6, then CAN_MIDx and CAN_MFIDx are set:
If the application associates a handler for each message ID, it may define an array of pointers to
functions:
When a message is received, the corresponding handler can be invoked using CAN_MFIDx reg-
ister and there is no need to check masked bits:
ID0 101000100100010010000100 0 11 00b
ID1 101000100100010010000100 0 11 01b
ID2 101000100100010010000100 0 11 10b
ID3 101000100100010010000100 0 11 11b
ID4 101000100100010010000100 1 11 00b
ID5 101000100100010010000100 1 11 01b
ID6 101000100100010010000100 1 11 10b
ID7 101000100100010010000100 1 11 11b
CAN_MIDx = 001 101000100100010010000100 x 11 xxb
CAN_MAMx = 001 111111111111111111111111 0 11 00b
CAN_MIDx = 001 101000100100010010000100 1 11 10b
CAN_MFIDx = 00000000000000000000000000000110b
void (*pHandler[8])(void);
unsigned int MFID0_register;
MFID0_register = Get_CAN_MFID0_Register();
// Get_CAN_MFID0_Register() returns the value of the CAN_MFID0 register
pHandler[MFID0_register]();
CAN_MFIDx
CAN_MIDx
AT91SAM7X512/256/128 Preliminary
Message Accepted
&
CAN_MAMx
==
Yes
No
&
Message Received
Message Refused
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