AT91M40800-33AU Atmel, AT91M40800-33AU Datasheet - Page 101

• Manufacturer Part Number: AT91M40800-33AU
• Description: IC ARM7 MCU 100 LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91M40800-33AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, UART/USART
• Peripherals: POR, WDT
• Number Of I /o: 32
• Program Memory Type: ROMless
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Package: 100TQFP
• Device Core: ARM7TDMI
• Family Name: 91M
• Maximum Speed: 33 MHz
• Operating Supply Voltage: 2.5|3.3 V
• Data Bus Width: 32 Bit
• Number Of Programmable I/os: 32
• Interface Type: EBI/USART
• Number Of Timers: 3
• Processor Series: AT91Mx
• Core: ARM7TDMI
• Data Ram Size: 8 KB
• Maximum Clock Frequency: 33 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JTRACE-ARM-2M, MDK-ARM, RL-ARM, ULINK2
• Minimum Operating Temperature: - 40 C
• Eeprom Memory: 0 Bytes
• Input Output: 32
• Interface: EBI/EMI, UART/USART
• Ios: 32
• Memory Type: ROMless
• Number Of Bits: 32
• Package Type: 100-pin LQFP
• Programmable Memory: 0 Bytes
• Timers: 3-16-bit
• Voltage, Range: 1.8-3.6 V
• Cpu Family: 91M
• Device Core Size: 32b
• Frequency (max): 33MHz
• Program Memory Size: Not Required
• Total Internal Ram Size: 8KB
• # I/os (max): 32
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 2.5/3.3V
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 1.8V
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 100
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Receiver
Asynchronous Receiver
Figure 38. Asynchronous Mode: Start Bit Detection
Figure 39. Asynchronous Mode: Character Reception
1354D–ATARM–08/02
Rate Clock
16 x Baud
Sampling
Example: 8-bit, parity enabled 1 stop
Sampling
RXD
RXD
periods
0.5 bit
True Start Detection
The USART is configured for asynchronous operation when SYNC = 0 (bit 7 of
US_MR). In Asynchronous Mode, the USART detects the start of a received character
by sampling the RXD signal until it detects a valid start bit. A low level (space) on RXD is
interpreted as a valid start bit if it is detected for more than 7 cycles of the sampling
clock, which is 16 times the baud rate. Hence a space which is longer than 7/16 of the
bit period is detected as a valid start bit. A space which is 7/16 of a bit period or shorter
is ignored and the receiver continues to wait for a valid start bit.
When a valid start bit has been detected, the receiver samples the RXD at the theoreti-
cal mid-point of each bit. It is assumed that each bit lasts 16 cycles of the sampling clock
(one bit period) so the sampling point is 8 cycles (0.5 bit periods) after the start of the bit.
The first sampling point is therefore 24 cycles (1.5 bit periods) after the falling edge of
the start bit was detected. Each subsequent bit is sampled 16 cycles (1 bit period) after
the previous one.
period
1 bit
D0
D1
True Start
Detection
D2
D3
D4
D5
D6
D7
Parity Bit
AT91X40 Series
Stop Bit
D0
101