AM1705 Datasheet, PDF (128/155 Pages) Texas Instruments – AM1705 ARM Microprocessor

AM1705
SPRS657 – FEBRUARY 2010
6.24.2 UART Electrical Data/Timing
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Table 6-83. Timing Requirements for UARTx Receive⁽¹⁾ (see Figure 6-45)
No.
PARAMETER
4 t_w(URXDB)
5 t_w(URXSB)
Pulse duration, receive data bit (RXDn)
Pulse duration, receive start bit
(1) U = UART baud time = 1/programmed baud rate.
MIN
0.96U
0.96U
MAX
1.05U
1.05U
UNIT
ns
ns
Table 6-84. Switching Characteristics Over Recommended Operating Conditions for UARTx Transmit⁽¹⁾
(see Figure 6-45)
No.
PARAMETER
MIN
MAX
UNIT
1 f_(baud)
Maximum programmable baud rate
D/E ^{(2) (3)} MBaud ⁽⁴⁾
2 t_w(UTXDB)
Pulse duration, transmit data bit (TXDn)
U-2
U+2
ns
3 t_w(UTXSB)
Pulse duration, transmit start bit
U-2
U+2
ns
(1) U = UART baud time = 1/programmed baud rate.
(2) D = UART input clock in MHz. The UART(s) input clock source is PLL0_SYSCLK2.
(3) E = UART divisor x UART sampling rate. The UART divisor is set through the UART divisor latch registers (DLL and DLH). The UART
sampling rate is set through the over-sampling mode select bit (OSM_SEL) of the UART mode definition register (MDR).
(4) Baud rate is not indicative of data rate. Actual data rate will be limited by system factors such as EDMA loading, EMIF loading, system
frequency, etc.
UART_TXDn
Start
Bit
3
2
Data Bits
5
4
UART_RXDn
Start
Bit
Data Bits
Figure 6-45. UART Transmit/Receive Timing
128 Peripheral Information and Electrical Specifications
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