PCIMX258CJM4A datasheet(115/144 Pages) FREESCALE

115 / 144 page

i.MX25 Applications Processor for Consumer and Industrial Products, Rev. 3

Freescale Semiconductor

115

3.7.19.1.2

UART Receive Timing in RS-232 Serial Mode

Figure 86 shows the UART receive timing in RS-232 serial mode, showing only 8 data bits and 1 stop bit.

Table 85 describes the timing parameter (UA2) shown in the figure.

–

Figure 86. UART RS-232 Serial Mode Receive Timing Diagram

3.7.19.2

UART Infrared (IrDA) Mode Timing

The following subsections describe the UART transmit and receive timing in IrDA mode.

3.7.19.2.3

UART IrDA Mode Transmit Timing

Figure 87 depicts the UART transmit timing in IrDA mode, showing only 8 data bits and 1 stop bit.

Table 86 describes the timing parameters (UA3–UA4) shown in the figure.

Figure 87. UART IrDA Mode Transmit Timing Diagram

Table 84. UART RS-232 Serial Mode Transmit Timing Parameters

Parameter

Symbol

Min.

Max.

Units

UA1

Transmit Bit Time

tTbit

1/Fbaud_rate

1 – T

ref_clk

1 F

baud_rate: Baud rate frequency. The maximum baud rate the UART can support is (ipg_perclk frequency)/16.

2 T

ref_clk: The period of UART reference clock ref_clk (ipg_perclk after RFDIV divider).

1/Fbaud_rate + Tref_clk

—

Table 85. UART RS-232 Serial Mode Receive Timing Parameters

Parameter

Symbol

Min.

Max.

Units

UA2

Receive bit time1

1 Note: The UART receiver can tolerate 1/(16 × Fbaud_rate) tolerance in each bit. But accumulation tolerance in one frame must

not exceed 3/(16

× Fbaud_rate).

tRbit

1/Fbaud_rate

2 – 1/(16

× Fbaud_rate)

2 F

baud_rate: Baud rate frequency. The maximum baud rate the UART can support is (ipg_perclk frequency)/16.

1/Fbaud_rate + 1/(16

× Fbaud_rate)

—

Bit 1

Bit 2

Bit 0

Bit 4

Bit 5

Bit 6

Bit 7

RXD

(input)

Bit 3

Start

Bit

STOP

BIT

Start

Bit

Possible

Parity

Bit

Par Bit

UA2

Bit 1

Bit 2

Bit 0

Bit 4

Bit 5

Bit 6

Bit 7

TXD

(output)

Bit 3

Start

Bit

STOP

BIT

Possible

Parity

Bit

UA3

UA4

PCIMX258CJM4A Datasheet(PDF) 115 Page - Freescale Semiconductor, Inc

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