AN2737

IAP example with SPI

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IAP example with SPI

This section describes how to perform basic IAP with the STM8 SPI peripheral. The STM8

device behaves like a standard SPI EEPROM slave which can communicate with any

master. In this application note, the Aardvark PC host adapter is used as the SPI master.

2.1

Hardware description

Figure 9 shows a typical hardware connection between the Aardvark host adapter as master

and the STM8 SPI peripheral as slave. This type of communication uses hardware NSS

management for the slave.

The following pins are connected together:

●

Aardvark MOSI and STM8 SPI MOSI.

●

Aardvark MISO and STM8 SPI MISO.

●

Aardvark SCK and STM8 SPI SCK.

●

Aardvark SS and STM8 SPI NSS.

Note:

When the STM8 evaluation board (STM8/128-EVAL) is used, the R34 resistor has to be

soldered on the R35 placement. This is to put the I/O of the micro-SD card level shifter in

high impedance state. To use the micro-SD card, the R34 resistor has to be soldered back

to its original place.

Figure 9.

Hardware connection between the Ardvark host adapter and the STM8

SPI

2.2

Firmware description

The current example is provided in the ZIP file attached to this AN.

It includes:

●

The SPI driver that supports all basic SPI communications.

●

The Flash, CLK, GPIO and LCD screen drivers.

STM8 SPI peripheral is the slave). As a result, the maximum STM8 SPI speed is 8 MHz.

R/W

Aardvark

host adapter

USB

MOSI

MISO

SCK

SS/NSS

PC + Aardvark

software

SPI

Slave

Master

STM8 device

Flash program

memory and

data EEPROM