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
2. CS = 0: command/program mode
→ LED, EN, OUTN are active.
→ 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“.
VDD PROG
VLED
R5
R2
T2
VDD
R6
R8
D1
epc110
INV1
AND1
T3
VDD33
VDD18
CS
LED/SCK
EN/SI
+
T1
C1
D4
8V2
PD
OUTN/SO
OUTH
S1
R1
D2
D3
GND
V_IN
V_OUT
VDD µC
Regulator 3.3V
ADJ
VDD
µController
R7
OUT PROG
R3 T4
CS
SCK
SO
BUF1
SI
OUT ESCK
IN
R4
GND
GND
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
EPC [ ESPROS PHOTONICS CORP ]
