Cirrus Logic EP93xx - Manual (Page 563)

DS785UM1 15-5
Copyright 2007 Cirrus Logic
UART2
EP93xx User’s Guide
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15
15.2.4 Enabling Infrared (Ir) Modes
15.3 UART2 Package Dependency
UART2 uses package pins RXD1 and TXD1. Pin RXD1 drives both the UART2 UART input
and the UART2 SIR input.
However, Syscon register DeviceCfg[28] (IonU2) controls what drives pin TXD1. See
Table 15-2 .
Therefore, to use any IrDA mode, FIR, MIR or SIR, set IonU2. To use UART2 as a UART,
clear IonU2.
15.3.1 Clocking Requirements
There are two clocks, PCLK and UARTCLK.
UARTCLK frequency must accommodate the desired range of baud rates:
Fuartclk(min) >= 32 x baud_rate(max)
Fuartclk(max) <= 32 x 65,536 x baud_rate(min)
The frequency of UARTCLK must also be within the required error limits for all baud rates to
be used.
To allow sufficient time to write the received data to the receive FIFO, UARTCLK must be less
than or equal to four times the frequency of PCLK:
Table 15-1. UART2 / IrDA Modes
Mode
DeviceCfg Register UART2Ctrl Register IrEnable Register
U2EN IonU2 SirEn UARTE EN[1] EN[0]
Disabled 0 x 0 0 0 0
UART2 1 0 0 1 0 0
SIR 1 1 1 1 0 1
MIR x 1 0 0 1 0
FIR x 1 0 0 1 1
Table 15-2. IonU2 Pin Function
IonU2 Pin TXD1 Function
0 UART2 UART is the output signal
1 Logical OR of IrDA output signal and UART2 SIR output signal