AT91M55800A-33CJ Atmel, AT91M55800A-33CJ Datasheet - Page 137

• Manufacturer Part Number: AT91M55800A-33CJ
• Description: IC ARM MCU 16BIT 176BGA
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91M55800A-33CJ

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 33MHz
• Connectivity: EBI/EMI, SPI, UART/USART
• Peripherals: POR, WDT
• Number Of I /o: 58
• Program Memory Type: ROMless
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 3.6 V
• Data Converters: A/D 8x10b; D/A 2x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 176-LFBGA
• Processor Series: AT91Mx
• Core: ARM7TDMI
• Data Bus Width: 32 bit
• Data Ram Size: 8 KB
• Interface Type: EBI, SPI, USART
• Maximum Clock Frequency: 33 MHz
• Number Of Programmable I/os: 58
• Number Of Timers: 10 bit
• Operating Supply Voltage: 3 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JTRACE-ARM-2M, MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: AT91EB55
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• On-chip Dac: 8 bit, 2 Channel
• Cpu Family: AT91
• Device Core: ARM7TDMI
• Device Core Size: 32b
• Frequency (max): 33MHz
• Program Memory Size: Not Required
• Total Internal Ram Size: 8KB
• # I/os (max): 58
• Number Of Timers - General Purpose: 6
• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (max): 3.6V
• Operating Supply Voltage (min): 2.7V
• Instruction Set Architecture: RISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 176
• Package Type: BGA
• For Use With: AT91EB55 - KIT EVAL FOR ARM AT91M55800A
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

18.3
18.3.1
1745F–ATARM–06-Sep-07
Receiver
Asynchronous Receiver
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 theoretical 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.
Figure 18-3.
Figure 18-4. Asynchronous Mode: Character Reception
Rate Clock
Example: 8-bit, parity enabled 1 stop
16 x Baud
Sampling
Sampling
RXD
RXD
Asynchronous Mode: Start Bit Detection
periods
0.5-bit
True Start Detection
period
1-bit
D0
D1
True Start
Detection
D2
D3
D4
D5
D6
AT91M5880A
D7
Parity Bit
Stop Bit
D0
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