OL2385SWUG datasheet(4/64 Pages) NXP

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OL2385SWUG

SIGFOX software driver

OL2385SWUG

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User guide

Rev. 2.1 — 6 April 2018

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Figure 2. 5 wire SPI diagram

A messaging protocol has been defined for SPI interface between OL2385 and host

microcontroller. The protocol governs the states of each of the five SPI interface pins,

as shown in Figure 3.

It is very important to note here that Host is the master and

always the initiator of the communication, which means that there cannot be an

independent transfer of bytes from OL2385 to host. The communication will take

place always by transfer of bytes from host to OL2385, and if a response is required

back only then data transfer will take place from OL2385 to host. The cases in which

such a response is desired is explained in further in Section 6.2.4.4 "SPI command

descriptions". The sequence of pin driving should take place strictly in the following

manner:

Note: By default, after a reset, OL2385 goes to low-power mode with CS pin

configured as wakeup pin. Before proceeding to the low-power mode, OL2385

configures all its pins to pulled-down configuration, except for CS and Ack pins

of SPI. CS and Ack pins are pulled high. For the low-power mode to work properly

without any current leakage, it is important to have the same settings of the pins

on MCU side. All pins on MCU should be pulled low and only CS and Ack should

be high.

1. Initially, the CS and Ack pins should be driven high on the MCU side. OL2385 as a

slave waits for the CS pin to be driven low by the host to start communication.

2. Host drives CS pin low to signal data transfer.

3. OL2385 drives Ack pin low to signal that it is ready for clocking and data transfer.

4. Host provides clock and writes data on MOSI

OL2385 reads the first byte of data. This is the length byte that describes how

many valid data bytes are to be followed on SDI, including itself. After receiving

all the bytes, OL2385 drives the Ack pin high to signal data is received successfully.

6. Host drives CS back to high again to signal data transfer from host to OL2385 is

complete.

The data is now decoded at OL2385 and processed according to its meaning. If a

response is required to be submitted back to host after processing, the following

sequence should then be initiated from step number 7:

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