Pepper Computer Modular Computers RS232 User Manual

SMART I/O User’s Manual

October 01, 1996

©1996 PEP Modular Computers GmbH

Page 6- 22

Chapter 6  Communications Modules

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:

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.

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

• AR : Automatic Reading Mode

• P

: Parity Enable/Disable

• RST : Encoder Reset Control

• ENI : Interrupt Masks

• PT : Parity Type (Odd/Even)

• SOT: Start Transmission

• DT : Data Type (Gray/Binary)

• CF : Data Clock Frequency • CM : Clear Match output

1

Internal 16-bit Status Register

Read Only

1

Internal 24-bit Control Register

Write Only

1

Internal 8-bit Identification Register

Read Only

1

Internal 24-bit Data Register

Read Only

1

Internal 24-bit Compare Register

Write Only

1

SPI compatible serial EEPROM

Read/Write

1

Optional SPI compatible serial Digital to Analog Converter Read/Write