AT91R40807-33AI Atmel, AT91R40807-33AI Datasheet - Page 102

• Manufacturer Part Number: AT91R40807-33AI
• Description: IC ARM7 MCU 176 TQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91R40807-33AI

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, UART/USART
• Peripherals: WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 136K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

Synchronous Receiver
Receiver Ready
Parity Error
Framing Error
Time-out
102
AT91X40 Series
When configured for synchronous operation (SYNC = 1), the receiver samples the RXD
signal on each rising edge of the Baud Rate clock. If a low level is detected, it is consid-
ered as a start. Data bits, parity bit and stop bit are sampled and the receiver waits for
the next start bit. See example in Figure 40.
Figure 40. Synchronous Mode: Character Reception
When a complete character is received, it is transferred to the US_RHR and the RXRDY
status bit in US_CSR is set. If US_RHR has not been read since the last transfer, the
OVRE status bit in US_CSR is set.
Each time a character is received, the receiver calculates the parity of the received data
bits, in accordance with the field PAR in US_MR. It then compares the result with the
received parity bit. If different, the parity error bit PARE in US_CSR is set.
If a character is received with a stop bit at low level and with at least one data bit at high
level, a framing error is generated. This sets FRAME in US_CSR.
This function allows an idle condition on the RXD line to be detected. The maximum
delay for which the USART should wait for a new character to arrive while the RXD line
is inactive (high level) is programmed in US_RTOR (Receiver Time-out). When this reg-
ister is set to 0, no time-out is detected. Otherwise, the receiver waits for a first character
and then initializes a counter which is decremented at each bit period and reloaded at
each byte reception. When the counter reaches 0, the TIMEOUT bit in US_CSR is set.
The user can restart the wait for a first character with the STTTO (Start Time-out) bit in
US_CR.
Calculation of time-out duration:
Example: 8-bit, parity enabled 1 stop
Sampling
SCK
RXD
True Start Detection
D0
Duration
D1
= Value x
D2
D3
4
D4
x
Bit period
D5
D6
D7
1354D–ATARM–08/02
Parity Bit
Stop Bit