Technical Description; Internal Baud Rate Generator; Control And Status Registers Definition - SeaLevel ACB-MP+4.PCI User Manual

Technical Description

The ACB-MP+4.PCI utilizes the Zilog 85230 Enhanced Serial Communications
Controller (ESCC) and includes a dedicated Z85230 per port. This chip features
programmable baud rate, data format and interrupt control. Refer to the ESCC Users
Manual, available from Zilog, for details on programming the 85230 ESCC chip.

Internal Baud Rate Generator

The baud rate of the ESCC is programmed under software control. The standard
oscillator supplied with the board is 7.3728 MHz. However, other oscillator values
can be substituted to achieve different baud rates.

Control and Status Registers Definition

The control and status registers occupy 12 consecutive I/O locations. The following
tables provide a functional description of the bit positions. X = do not care.
Base Mode D7
+4 RD 0
+5 RD 485CLK
+5 WR 485CLK
+6 RD 0
+6 WR X
+7 RD X
+14 RD SD7
+15 RD SD15
Field
IRQST SCC interrupt status:
DSRA:
DSRA
LLA Local Loopback:
RLA Remote Loopback:
TSET clock source:
TSETSLA
RXCOPTA RXCOPTA:
SYNCA _RTS:
SYNCA_RTS
SYNCA_CTS SYNCA_CTS:
485CLK TSET switches with TXD:
ECHO enable:
ECHOA
AM0 – AM3 I/O mode select. See table for valid interface options.
SD0 – SD15 Optional security feature. Unique value per customer or application.
Note: Default values are listed in bold
© Sealevel Systems, Inc.
D6 D5
IRQST 0
ECHOA SYNCA_RTS
ECHOA SYNCA_RTS
0 0
X X
X X
SD6 SD5
SD14 SD13
1 = No interrupt pending on ESCC
1 = DSRA not active
1 = LL set
1 = RL set
1= Received TXC as source
1= Selects SCC PCLK for RTXCA
1 = SYNCA connected to RTS
1 = SYNCA connected to CTS
1 = clk switches
1 = echo disabled
D4 D3
0 0
SYNCA_CTS AM3
SYNCA_CTS AM3
0 RLA
X RLA
X IRQST4
SD4 SD3
SD12 SD11
Description
- 5 -
D2 D1
0 0
AM2 AM1
AM2 AM1
LLA TSETSLA RXCOPTA
LLA TSETSLA RXCOPTA
IRQST3 IRQST2
SD2 SD1
SD10 SD9
0 = Interrupt pending on ESCC.
0 = DSRA active
0 = LL not set
0 = RL not set
0 = TRXCA as source
0 = Selects received RXC for
RTXCA
0 = SYNCA is high
0 = SYNCA is high
0 = no CLK switching
0 = echo enabled
0 = High Impedance
Default value = FFFF
ACB-MP+4.PCI User Manual
D0
DSRA
AM0
AM0
IRQST1
SD0
SD8