EPC120 EPC [Espros Photonics corp], EPC120 Datasheet - Page 18

• Manufacturer Part Number: EPC120
• Description: Fully integrated Light-Barrier Chips with 2-Wire Bus Interface
• Manufacturer: EPC [Espros Photonics corp]

General Description
The SPI interface allows the microcontroller to communicate with the sensors over the 2-wire bus system via the interface device.
While data are sent to the interface chip by the microcontroller, the result of the last (or more generally: a previous) command is sent from the
interface chip to the microcontroller according to the SPI protocol. The timing diagram is shown in Figure 16).
Timing Specification SPI Interface
Command Overview
© 2011 ESPROS Photonics Corporation
Characteristics subject to change without notice
10. SPI Interface
Communication is based on telegrams, which are sent and received over the 2-wire bus. Such telegrams are initiated by the respective
command to the SPI interface. The epc10x chips accept two types of commands:
The first bit in the data stream from the microprocessor to the interface chip (SI pin) defines whether it is a command to the interface chip (a
“0”) or the the chips on the 2-wire bus (a ”1”).
f
t
t
t
t
t
SCK
H
SU
1
rf
D
Symbol
/ t
/ t
/ t
rfSCK
L
SCK
Hold
CS
SI
1.
2.
CS
SCK
SI
SO
Commands which communicate to the interface chips, also called “Direct Commands” ( Figure 17).
Commands which communicate to the chips at the 2-wire bus, also called “Broadcast Commands” ( Figure 18).
Parameter
SCK Clock frequency
HIGH and LOW period of SCK
Set-up and hold time SI
Edge time CSB - SCK
Rise / fall time
Data valid after SCK edge
t
D
t
1
Figure 17: Communication to the interface device (Direct Command)
C
0
t
L
Command
t
SU
C
1
C
2
Conditions/Comments
SO, SCK
SO
R
0
Figure 16: SPI bus timing
Register Address or Cmd Extension
R
1
R
18
2
R
3
R
4
D
0
Min.
D
50
15
50
1
Data
Values
Typ.
D
n
Datasheet epc12x - V2.1
Max.
10
20
20
www.espros.ch
epc120
Units
MHz
ns
ns
ns
ns
ns