Register Description; Control Register - PEP Modular Computers Modular Computers RS485 User Manual

SMART I/O User's Manual

6.2.7 Register Description

The SM-SSI SMART-Module connected to a SMART I/O slot uses the SPI
transparent mode for on-board data reading and writing and 5 parallel lines
for data selection. On board are a set of registers and peripherals shown in
the table below:
N o .
1 Internal 16-bit Status Register
1 Internal 24-bit Control Register
1 Internal 8-bit Identification Register
1 Internal 24-bit Data Register
1 Internal 24-bit Compare Register
1 SPI compatible serial EEPROM
1 Optional SPI compatible serial Digital to Analog Converter Read/Write
Due to the fact that SPI transmissions are full duplex, some read only regis-
ters are accessed at the same time as write only registers in order to optimize
data transmission. Therefore, when the Control Register is written to, simul-
taneously the Status Register is read and similarly when writing to the
Compare Register, the Data Register is read.
256 bytes of serial EEPROM contain the module ID number and production
data although and further space has been allocated for future use.

6.2.7.1 Control Register

The 24-bit control register is divided into three sub-registers which are
cleared after a power-on reset and control:
• FDL: Format Data Length
• P : Parity Enable/Disable
• ENI : Interrupt Masks
• SOT: Start Transmission
• CF : Data Clock Frequency
Page 6- 22
Description
• AR : Automatic Reading Mode
• RST : Encoder Reset Control
• PT : Parity Type (Odd/Even)
• DT : Data Type (Gray/Binary)
• CM : Clear Match output
©1996 PEP Modular Computers GmbH
Chapter 6 Communications Modules
Direction
Read Only
Write Only
Read Only
Read Only
Write Only
Read/Write
October 01, 1996