AT91SAM7A1-AU Atmel, AT91SAM7A1-AU Datasheet - Page 291

• Manufacturer Part Number: AT91SAM7A1-AU
• Description: IC ARM7 MCU 32BIT ROMLESS144LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7A1-AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 40MHz
• Connectivity: CAN, EBI/EMI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 49
• Program Memory Type: ROMless
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 144-LQFP
• For Use With: AT91SAM7A1-EK - BOARD EVAL FOR AT91SAM7A1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

25.15.1.3
25.15.2
6048B–ATARM–29-Jun-06
mMinimum Frequency
Frequency Limitation
Cancelling a Pending Transmission
A pending transmission may be cancelled but users must respect the following steps:
This assures that if the frame transmission process has started before the cancel has been
requested, the frame transmitted has the correct identifier, data and control.
In order to ensure proper CAN operation, the CAN module should be clocked with a minimum
frequency. This minimum frequency can be computed with the following formula:
For example, for a application using only one channel in transmission, a 32-channel CAN and
a CAN baud rate of 1 MHz, the minimum frequency is 22 MHz
(22 MHz = (1 + 3*1 + 2*31)/3µs).
• Clear the CHANEN flag in the CAN_CRx register. Note that other bits of this register
• Wait for a minimum delay before setting a new reception or transmission in this channel.
• Afterwards, the frame related registers (CAN_IRX, CAN_DRAX, CAN_DRBX and
=
should not be modified (a read-modify is mandatory).
This delay depends on the identifier length configured in the pending transmission to
cancel. The delay is:
CAN_CRX registers) can be modified.
1
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
– for a standard frame (11-bit length identifier):
– for an extended frame (29-bit length identifier):
+
97 system clock periods + 106 CAN bit time
97 system clock periods + 131 CAN bit time
3
Number of channel enable in transmission
3
CAN Bit Time
+
2
Reminder channels
AT91SAM7A1
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