IN16C1054 Ver la hoja de datos (PDF) - IK Semicon Co., Ltd

Número de pieza

componentes Descripción

Fabricante

IN16C1054

Quard Uart with 256-Byte FIFO

IK Semicon Co., Ltd 

IN16C1054

6.2.1 Auto-RTS

To enable Auto-RTS, EFR[6] should be set to ‘1’. Once enabled, RTS# outputs ‘0’. If the

number of received data in RX FIFO is larger than the value stored in FUR, RTS# will be

changed to ‘1’ and if not, holds ‘0’. This state indicates that RX FIFO can accept more

data. After RTS# changed to ‘1’ and reported to the CPU that it cannot accept more data,

the CPU reads the data in RX FIFO and then the amount of data in RX FIFO reduces.

When the amount of data in RX FIFO equals the value written in FLR, RTS# changes to

‘0’ and reports that it can accept more data. That is, if RTS# is ‘0’ now, RTS# is not

changed to ‘1’ until the amount in RX FIFO exceeds the value set in FUR. But if RTS# is

‘1’ now, RTS# is not changed to ‘0’ until the amount in RX FIFO equals the value written

in FLR.

The value of FUR and FLR is determined by FIFO mode. If FCR[7:6] holds ‘00’, ’01’, ‘10’,

and ‘11’, FUR stores 8, 16, 56, and 60, respectively. And if FCR[5:4] holds ‘00’, ’01’, ‘10’,

and ‘11’, FLR stores 0, 8, 16, and 56, respectively in 64-byte FIFO. In 256-byte FIFO

mode, users can write FUR and FLR values as they want and use them. But the value of

FUR must be larger than that of FLR. While Auto-RTS is enabled, you can verify if RTS#

is ‘0’ or ‘1’ by FSR[5]. If FSR[5] is ‘0’, RTS# is ‘0’ and if ‘1’, RTS# is ‘1’, too.

When IER[6] is set to ‘1’ and RTS# is changed from ‘0’ to ‘1’ by Auto-RTS function,

interrupt occurs and it is displayed on ISR[5:0]. Interrupts by Auto-RTS function are

removed if MSR is read. RTS# is changed from ‘0’ to ‘1’ after the first STOP bit is

received. Figure 4 shows the RTS# timing chart while Auto-RTS is enabled.

In Figure 4, Data Byte n-1 is received and RTS# is deasserted when the amount of data

in RX FIFO is larger than the value written in FUR. UART completes transmitting new

data (DATA BYTE n) which has started being transmitted even though external UART

recognizes RTS# has been deasserted. After that, the device stops transmitting more

data. If CPU reads data of RX FIFO, the value of RCR decreases and then if that value

equals that of FLR, RTS# is asserted for external UART to transmit new data.

RXD

START DATA BYTE n-1 STOP

START

DATA BYTE n

STOP

RTS#

IOR#

DATA BYTE 1

DATA BYTE 2

RCR[7:0]

FUR + 0

Figure 4: RTS# Functional Timing

FUR + 1

FUR -0

FUR - 1 FUR - 0

START

DATA BYTE n

FLR + 1

FLR + 0

Rev. 00

Share Link: