AN4494

SPI interface

6.

The microcontroller reads 5 bytes from SPI and [02,7F,00,06,00] is expected, meaning

6 bytes to read

7.

The microcontroller reads 6 bytes from SPI and [04, FF, 03, 01, 00, 01] is expected

8.

The microcontroller raises the CS again

Figure 3: BlueNRG SPI transaction on HW reset

The bytes in step 7 should be interpreted as an HCI vendor specific (VS) event packet

(refer to Section 2.3: "Test description").

When the BlueNRG firmware is started normally, it gives a Blue_Initialized_Event to the

user to indicate the system has started.

The following is a detailed interpretation about this specific HCI VS event packet:

Table 3: Blue_Initialized_Event

Bytes

Description

04

It indicates an HCI Event Packet

FF

It is a vendor specific HCI event (Event code 0xFF)

03

HCI VS event parameter total length

01 00

BLUE_INITIALIZED event code

01

Reason code x BLUE_INITIALIZED event: Application started properly

3.6

Expected results

The bytes sent by the BlueNRG are described in Section 3.5: "Test procedure".

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