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.
J10
J11
J12
J13
X2
X4
X8
SPAD
Figure 3 --- Factory default clock rate and options settings
2.4.1 Enable Scratchpad Register (SPAD, J13)
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.
J10
J11
J12
J13
X2
X4
X8
SPAD
Figure 4 --- Enable scratchpad registers
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