Scratchpad Register (Spr); Enhanced Feature Register (Efr) - Philips SC16C2550 Manual

Philips Semiconductors

7.9 Scratchpad Register (SPR)

7.10 Enhanced Feature Register (EFR)

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Product data
Dual UART with 16 bytes of transmit and receive FIFOs and IrDA
Table 19: Modem Status Register bits description
Bit Symbol
1 MSR[1]
0 MSR[0]
[1] Whenever any MSR bit 0-3 is set to logic 1, a Modem Status Interrupt will be generated.
The SC16C2550 provides a temporary data register to store 8 bits of user
information.
Enhanced features are enabled or disabled using this register.
Bits 0 through 4 provide single or dual character software flow control selection.
When the Xon1 and Xon2 and/or Xoff1 and Xoff2 modes are selected, the double
8-bit words are concatenated into two sequential numbers.
Table 20: Enhanced Feature Register bits description
Bit Symbol Description
7 EFR[7] Automatic CTS flow control.
Logic 0 = Automatic CTS flow control is disabled (normal default
condition).
Logic 1 = Enable Automatic CTS flow control. Transmission will stop
when CTS goes to a logical 1. Transmission will resume when the CTS
pin returns to a logical 0.
6 EFR[6] Automatic RTS flow control. Automatic RTS may be used for hardware flow
control by enabling EFR[6]. When Auto-RTS is selected, an interrupt will
be generated when the receive FIFO is filled to the programmed trigger
level and RTS will go to a logic 1 at the next trigger level. RTS will return to
a logic 0 when data is unloaded below the next lower trigger level
(programmed trigger level 1). The state of this register bit changes with the
status of the hardware flow control. RTS functions normally when
hardware flow control is disabled.
0 = Automatic RTS flow control is disabled (normal default condition).
1 = Enable Automatic RTS flow control.
Rev. 03 — 19 June 2003
Description
∆DSR
[1]
Logic 0 = No DSR change (normal default condition).
Logic 1 = The DSR input to the SC16C2550 has changed state
since the last time it was read. A modem Status Interrupt will be
generated.
∆CTS
[1]
Logic 0 = No CTS change (normal default condition).
Logic 1 = The CTS input to the SC16C2550 has changed state
since the last time it was read. A modem Status Interrupt will be
generated.
SC16C2550
encoder/decoder
...continued
© Koninklijke Philips Electronics N.V. 2003. All rights reserved.
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