3. Instruction Set

The SPI interface allows the user to communicate with the epc610 chip. The graph of the principle communication flow is in Figure 13.

Starting a measurement, reading the result and setting the correct user parameters for operation are the main functions. All configurations

are set at run-time, are loaded immediately and are not stored in the chip.

The user can adapt the epc610 chip to his needs and application. For this reasons, the device has a SPI interface and a built-in memory

for the corresponding parametrization.

■ Sets operating parameters.

■ Triggers the measurement sequence.

■ Provides data access by a read function.

■ Allows reloading of the factory configuration.

All these functionalities are described in detail in chapter 3.4.: Start-up / load Parameter and configuration memory.

3.1. SPI interface

How the hardware needs be connected is shown in the schematic of Figure 26.

LED

NC3

LEDF

VREF

VDDIO

VDDHPX

VDDPX

VDDCP

VDDBS

XTAL1

XTAL2

VDDM

VDDT

nSS

SCLK

MOSI

MISO

VDDPLL

VDDCORE

GNDPLL

GNDA

GND

VDD

epc610

GND

VDD

Microprocessor

with SPI

VDD 8.5V

GND

GND

+5V

nSS

SCLK

MOSI

MISO

SPI:

GNDLED

Figure 26: Schematic of the SPI connection

The interface is for single slave use. It is targeted to operate up to a 10MHz clock frequency. While data is sent from the microprocessor to

the epc610 chip, the result of the last (or more generally of the previous command) is sent back according the SPI protocol in Figure 28.

One complete SPI frame consists of 16 bits (Word access), split into:

■ 2 bit command ID (CID) or response ID (RID)

■ 6 bit read or write address

■ 8 bit data

The timing of the SPI frame is shown in in Figure 27 and of the SPI hardware bus Figure 28 . At the target SPI frequency of 10MHz, the

access time for one SPI frame is <1.7μs.

nSS

SCLK

MOSI

MISO

CID [1:0]

address [5:0]

data [7:0]

response to previous access [13:0]

RID

[1:0]

Chip selection and

resynchronization

Serial clock signal

driven by microprocessor

Serial data input

Serial data output

Figure 27: SPI frame 16 bit

© 2014 ESPROS Photonics Corporation

Characteristics subject to change without notice

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Datasheet epc610 - V1.7

www.espros.ch