Quatech ES-100 user manual Fifo Control Register 16550 only, RXT0

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FIFO CONTROL REGISTER (16550 only)

This register, which applies only to the 16550 UART, is a write-only register located at I/O address [base+2]. It is used to enable the FIFO mode, clear the FIFOs, set the threshold level for the receive FIFO to generate interrupts, and to set the mode under which the device uses DMA. Note that DMA mode is NOT supported by the ES-100D.

BIT

 

 

DESCRIPTION

 

 

 

7

RXT1 ---

Receiver FIFO Trigger Level (16550 only):

6

RXT0 ---

Determines the trigger level for the receiver FIFO interrupt

RXT1

RXT0

Receiver FIFO trigger level (bytes)

 

 

 

 

0

0

1

 

 

0

1

4

 

 

1

0

8

 

 

1

1

14

5

0 --- reserved

 

 

 

 

 

 

 

 

4

0 --- reserved

 

 

 

 

 

 

 

3

DMAM --- DMA mode select (16550 only):

 

 

When set (logic 1), RxRDY and TxRDY change from mode 0 to mode 1 for DMA transfers.

 

(DMA mode is not supported on the ES-100D.)

 

2

XRST --- Transmit FIFO reset (16550 only):

 

 

When set (logic 1), all bytes in the transmitter FIFO are cleared and the counter is reset. The

 

shift register is not cleared. XRST is self-clearing.

1

RRST --- Receive FIFO reset (16550 only):

 

 

When set (logic 1), all bytes in the receiver FIFO are cleared and the counter is reset. The

 

shift register is not cleared. RRST is self-clearing.

0

FE --- FIFO enable (16550 only):

 

 

When set (logic 1), enables transmitter and receiver FIFOs. When cleared (logic 0), all bytes

 

in both FIFOs are cleared. This bit must be set when other bits in the FIFO control register

 

are written to or the bits will be ignored.

 

 

Figure 17 --- 16550 FIFO Control Register bit definitions

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Quatech ES-100D User's Manual

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Contents ES-100 Page Warranty Information Page FCC Class B EC Council Directive 89/336/EECGeneral Information Port Address IRQ InstallationDiagram of ES-100D Addressing Ports Setting the addressExamination of a serial port base address Interrupt Level IRQ Interrupt SharingInterrupt Status register Interrupt Status Register contents This page intentionally left blank External Connections ES-100D connector definitions Channel Output ConfigurationES-100D output connectors Serial Port Functional Description Dlab Accessing the Serial Port registersInterrupt Identification Register Interrupt Enable RegisterInterrupt Identification Register bit definitions RXT0 Fifo Control Register 16550 onlyEPS PEN Parity Line Control RegisterModem Control Register bit definitions Modem Control RegisterLine Status Register bit definitions Line Status RegisterScratchpad Register Modem Status RegisterWhen the receiver Fifo and receiver interrupts are enabled Fifo Interrupt Mode Operation 16550 Uart onlyFifo polled mode operation 16550 Uart only Value Values % Baud Rate Selection16450 16550 optional SpecificationsComputer will not boot up TroubleshootingVersion March Quatech Inc, ES-100 Manual