AT91SAM7X128 Atmel, AT91SAM7X128 Datasheet - Page 319

• 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
If STTTO is performed, the counter clock is stopped until a first character is received. The idle
state on RXD before the start of the frame does not provide a time-out. This prevents having to
obtain a periodic interrupt and enables a wait of the end of frame when the idle state on RXD is
detected.
If RETTO is performed, the counter starts counting down immediately from the value TO. This
enables generation of a periodic interrupt so that a user time-out can be handled, for example
when no key is pressed on a keyboard.
Figure 30-14
Figure 30-14. Receiver Time-out Block Diagram
Table 30-8
Table 30-8.
• Obtain an interrupt while no character is received. This is performed by writing US_CR with
RETTO
on RXD before a new character is received will not provide a time-out. This prevents having
to handle an interrupt before a character is received and allows waiting for the next idle state
on RXD after a frame is received.
the RETTO (Reload and Start Time-out) bit at 1. If RETTO is performed, the counter starts
counting down immediately from the value TO. This enables generation of a periodic interrupt
so that a user time-out can be handled, for example when no key is pressed on a keyboard.
Character
Received
Baud Rate
STTTO
gives the maximum time-out period for some standard baud rates.
bit/sec
14400
19200
28800
33400
shows the block diagram of the Receiver Time-out feature.
1 200
2 400
4 800
9 600
600
Maximum Time-out Period
1
D
AT91SAM7X512/256/128 Preliminary
Clear
Q
Baud Rate
Clock
Clock
Bit Time
1 667
833
417
208
104
µs
69
52
35
30
16-bit Time-out
Counter
TO
Load
16-bit
Value
0
Time-out
109 225
54 613
27 306
13 653
6 827
4 551
3 413
2 276
1 962
=
ms
TIMEOUT
319