Sharp ER-A570, Service Manual

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Pin No. Symbol Pin name and function
Input/
Output
26 LOC/DTR Loop On Line Control/Data Terminal Ready output. This pin functions as the DTR in any mode other
than Loop mode (CR3b5 = 0). It is set Low if CR3b7 is set to one, and is set High when the same bit is
set to zero.
When in the Loop mode (CR3b5 = 1), this pin functions as the LOC, which is used to control the
external loop interface hardware between On Loop and Off Loop.
If CR3b7 is set to zero, this pin is set High when RxD = 01111111 is detected, causing the hardware to
go into the On Loop. If CR3b7 is set to zero, this pin is set High when RxD = 11111111 is detected,
causing the hardware to return to the Off Loop.
If the RESET input is set Low, CR3b5 is set to zero (Non-Loop Mode), which sets CR3b7 to zero. As a
result, this pin issues a High level signal.
(Loop On Line Control/Data Terminal Ready Output)
Out
28 CTS Clear to Send input. Setting this pin to High disables ST1b6 and related IRQ.
If SR1b4 is set and this pin is enabled, an IRQ is issued. Low-to-High transition at the CTS input is set
in SR1b4, which is cleared by CR2b6 or CR1b7.
(Clear to Send Input)
In
27 DCD Loop On Line Control/Data Terminal Ready output. Setting this pin to High resets the Receiver register
and sets SR2b5, which causes an IRQ to be issued if enabled. Low-to-High transition at the DCD input
is set in ST2b5, which cleared by CR2b5 or CR1b6.
(Loop On Line Control/Data Terminal Ready Output)
In
4  12