With NO jumpers on J13 or J20 the mode selection is RCLK=TCLK. With Jumpers installed on J13 or J20 the mode selection is RCLK=AUXIN.
2.3.4 TGL0_SEL1,0, TGL1_SEL1,0 (J15,14,22,21)
With NO jumpers on J15,14, or J22,21 the mode selection is TXEN=1. With Jumpers installed on J14 or J21 and NO jumpers on J15 or J22, the mode selection is TXEN=DTR. With Jumpers installed on J15 or J22 and NO jumpers on J14 or J21, the mode selection is TXEN=RTS. With Jumpers installed on J15, J14 or J22, J21, the mode selection is TXEN=”Auto Toggle”.
2.3.5 RXEN0_SEL, RXEN1_SEL (J16, 23)
With NO jumpers on J16 or J23 the mode selection is RXEN=1. With Jumpers installed on J16 or J23 the mode selection is RCLK=!TXEN.
2.4 Clock Rate and Optional Registers
Figure 3 shows the jumper configuration as shipped from the factory, with two spare jumpers applied in neutral positions. Remove one or both and apply as shown in following subsections to set optional features.
J2
J4
J5
SPAD
X4
X2
Figure 3 --- Factory default clock rate and options settings
2.4.1 Enable Scratchpad Register (SPAD, J2)
In the default configuration, an Interrupt Status Register and an Options Register (see page 10) replace the scratchpad (base address + 7) of each UART. If the SPAD jumper is applied as in Figure 4, the UART scratchpad registers are enabled, and the Interrupt Status Register and the Options Register are not available.
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