Owner's manual

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