epc110

SPI Interface

The serial peripheral interface (SPI) allows the micro-controller to communicate with the epc110 device. It allows the access to the internal

memory of the chip for parameter setting and programming for configuration or in a dynamic mode to change parameters on the fly.

Hardware interface

This functionality is given by double-used pins: LED/ SCK, EN/SI, OUTN/SO.

The signal CS does the selection, if the operation mode or the command/program mode is active:

1.

CS = 1: operation mode

→ LED, EN, OUTN are active.

2.

CS = 0: command/program mode

→ SCK, SI, OUTN are active.

As long as CS = 0 the pin LED/SCK is set to high-ohmic and defined as input pin.

IMPORTANT NOTICE:

Due to fact of the advantage of the flexibility in use of this devic e the responsibility of any possible hardware, LED load or LED driver conflicts

have to be handled by the user and are depending of the final application schematic. Main items to take care of are:

•

Double-use as input as well output of LED/ SCK signals/line. For non-standalone application a well done decoupling of the signals is

needed.

•

Parameter setting and programming of the device in final application environment e.g. if LED and LED drivers are not designed for

continuous mode application, risk of overloading.

•

During SPI access of the device in final application environment e.g. if LED and LED drivers are not designed for continuous mode

application, risk of overloading.

Possible solutions are discussed at the example of the principal schematic “ Figure 13: Hardware interface micro-controller – epce110 “.

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25.01.2011

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LST

VDD µC

+

C1

R2

VLED

T1

D1

R1

BUF1

INV1

AND1

V_IN

V_OUT

ADJ

Regulator 3.3V

LED/SCK

EN/SI

OUTN/SO

OUTH

CS

VDD33

VDD18

PD

GND

VDD

epc110

GND

VDD PROG

SCK

SO

SI

CS

GND

VDD

µController

OUT ESCK

IN

R4

R3

R5

T3

T2

T4

OUT PROG

D4

8V2

R7

D2

D3

R6

R8

S1

Figure 13: Hardware interface micro-controller – epce110

1.

Mode selection: Operation mode - Parameter/Program mode

As long the device is not connected to an LED driver, the access to the SPI interface is allowed while CS = 0. This can simply be

done by the switch S1 before power up the circuit. In this case the output LED/ SCK will not be driven as an output.

2.

Run-time access of SPI interface

To have no conflicts together with a micro-processor on the bus line LED/SCK (Output/input) during run-time operation in this

example, the decoupling and interfacing of the LED/ SCK line is done by the tristate buffer BUF1, the additional input IN and

additional output enable SCK (OUT ESCK). While the LED is in operation, driven by the epc110, OUT ESCK = 0 will tristate the

buffer and the SCK line from the micro-processor. With the input IN the micro-processor can read the status of the LED/ SCK line

after the buffer for finding the correct transition time.

© 2011 ESPROS Photonics Corporation

Characteristics subject to change without notice

16

Datasheet epc110 - V2.1

www.espros.ch