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void MAX72xx_init(void);

void MAX72xx_write(unsigned char address, unsigned char value);

MAX72xx.c

#include "MAX72xx.h"

void MAX72xx_init(void)

{

GPIO_Init(CS_port, CS_pin, GPIO_MODE_OUT_PP_HIGH_FAST);

MAX72xx_write(shutdown_reg, run_cmd);

MAX72xx_write(decode_mode_reg, 0x00);

MAX72xx_write(scan_limit_reg, 0x07);

MAX72xx_write(intensity_reg, 0x04);

MAX72xx_write(display_test_reg, test_cmd);

delay_ms(10);

MAX72xx_write(display_test_reg, no_test_cmd);

}

void MAX72xx_write(unsigned char address, unsigned char value)

{

while(SPI_GetFlagStatus(SPI_FLAG_BSY));

GPIO_WriteLow(CS_port, CS_pin);

SPI_SendData(address);

while(!SPI_GetFlagStatus(SPI_FLAG_TXE));

SPI_SendData(value);

while(!SPI_GetFlagStatus(SPI_FLAG_TXE));

GPIO_WriteHigh(CS_port, CS_pin);

}

Explanation

This time we are again using the max peripheral and CPU clock:

CLK_HSIPrescalerConfig(CLK_PRESCALER_HSIDIV1);

CLK_SYSCLKConfig(CLK_PRESCALER_CPUDIV1);

….

CLK_PeripheralClockConfig(CLK_PERIPHERAL_SPI, ENABLE);

We also need to set the GPIOs:

#define CS_pin GPIO_PIN_4

#define CS_port GPIOC

….

GPIO_DeInit(GPIOC);

GPIO_Init(CS_port, CS_pin, GPIO_MODE_OUT_PP_HIGH_FAST);

GPIO_Init(GPIOC, ((GPIO_Pin_TypeDef)GPIO_PIN_5 | GPIO_PIN_6), GPIO_MODE_OUT_PP_HIGH_FAST);

Note we can use definitions to make things meaningful. The GPIOs should be configured as fast I/Os

because SPI communication is faster than simple GPIO operations.

STMicroelectronics STM8 User Manual

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