M-arch (fanwai 10) gd32l233 evaluation -spi drive DS1302

Preface

Good architecture , High yield like sows .

Interface modification , The effect comes out .

On the second day of commencement , Do something about it SPI drive DS1302.

keyword ：GD32,SPI,DS1302, Three line SPI, Half duplex SPI

SPI

Serial peripheral interface （Serial Peripheral Interface, Abbreviation for SPI） Provides the basis for SPI Data sending and receiving function of the protocol , It can work in master or slave mode .SPI The interface supports hardware CRC Full duplex and simplex modes for calculation and verification . There are some SPI The mouth also supports SPI Four wire host mode .

The conventional SPI The signal description is shown in the figure below ：

routine SPI Signal description

DS1302

DS1302 It's the United States DALLAS The company has launched a small current charging capacity of low-power real-time clock chip . It can be used for years 、 month 、 Japan 、 Zhou 、 when 、 branch 、 Seconds to time , And it has many functions such as leap year compensation .（ Baidu Encyclopedia ）

DS1302 Pin configuration ：

DS1302 Pin configuration

DS1302 The temporal ：

DS1302 sequential

You can see ： except CE The high and low levels are different , This timing is similar to half duplex SPI It's the same .

Half duplex SPI

DS1302 Register configuration ：

DS1302 register

DS1302 The clock frequency of ：

DS1302 clock frequency

Three line SPI drive DS1302

Half duplex SPI Basic initialization of ：

• Single line transmission mode

• data 8 position

• Host mode

• Clock idle low level , The first edge reads data

• NSS Soft

• frequency division ： according to DS1302 Configuration to , commonly 1M More suitable .

• LSB

Sending process ：

• Set to send mode

• CE Can make

• Sending address

• send data

• CE Disability

Receiving process ：

• Set to send mode

• CE Can make

• Sending address

• Set to receive mode

• Wait for data reception to complete

• CE Disability

• Switch to send mode , Cut off SPI Clock signal

• Reading data , wait for SPI Call it a day

simulation IO drive DS1302

A little （ I wrote about , Don't stick ）

SPI drive DS1302

Pit father's episode ：

SPI It's usually AF5, For the results SPI1 Pin is PB13,PB14,PB15, They are AF6, It's a hole 2 Hours , That's bullshit .

I hate debugging hardware , I really hope chip manufacturers can design more hardware by software engineers idea.

SPI initialization ：

#define DS1302_USING_SPI

/* SPI0:PA5-SCK-SPI_SCK PA6-CE-SPI_MISO PA7-DATA-SPI_MOSI */
/* SPI1:PB13-SCK-SPI_SCK PB14-CE-SPI_MISO PB15-DATA-SPI_MOSI */

#define CURRENT_SPI     SPI1
#define CURRENT_SPI_RCU RCU_SPI1

#define RTC_RCU         RCU_GPIOB
#define RTC_GPIO        GPIOB
#define RTC_SCK_PIN     GPIO_PIN_13
#define RTC_CE_PIN      GPIO_PIN_14
#define RTC_DATA_PIN    GPIO_PIN_15

#ifdef DS1302_USING_SPI
#define READ_MODE   spi_disable(CURRENT_SPI); \
                    spi_bidirectional_transfer_config(CURRENT_SPI, SPI_BIDIRECTIONAL_RECEIVE); \
                    spi_enable(CURRENT_SPI);
#define WRITE_MODE  spi_disable(CURRENT_SPI); \
                    spi_bidirectional_transfer_config(CURRENT_SPI, SPI_BIDIRECTIONAL_TRANSMIT); \
                    spi_enable(CURRENT_SPI);

#define  CE_HIGH    gpio_bit_set(RTC_GPIO, RTC_CE_PIN);
#define  CE_LOW     gpio_bit_reset(RTC_GPIO, RTC_CE_PIN);

#else
#endif

void spi1_init(void)
{
    spi_parameter_struct spi_init_struct;

    spi_i2s_deinit(CURRENT_SPI);
    rcu_periph_clock_enable(CURRENT_SPI_RCU);

    /* SPI_MOSI */
    gpio_init_af_mode(RTC_RCU, RTC_GPIO, RTC_DATA_PIN, GPIO_OSPEED_50MHZ, GPIO_AF_6);
    /* SPI_SCK */
    gpio_init_af_mode(RTC_RCU, RTC_GPIO, RTC_SCK_PIN, GPIO_OSPEED_50MHZ, GPIO_AF_6);
    /* RTC CE */
    gpio_init_output_mode(RTC_RCU, RTC_GPIO, RTC_CE_PIN, GPIO_OSPEED_50MHZ, 0);
    CE_LOW;

    /* SPI parameter config */
    spi_init_struct.trans_mode           = SPI_TRANSMODE_BDTRANSMIT;
    spi_init_struct.device_mode          = SPI_MASTER;
    spi_init_struct.frame_size           = SPI_FRAMESIZE_8BIT;
    spi_init_struct.clock_polarity_phase = SPI_CK_PL_LOW_PH_1EDGE;
    spi_init_struct.nss                  = SPI_NSS_SOFT;
    spi_init_struct.prescale             = SPI_PSC_16;
    spi_init_struct.endian               = SPI_ENDIAN_LSB;
    spi_init(CURRENT_SPI, &spi_init_struct);

    /* enable */
    spi_enable(CURRENT_SPI);
}

DS1302 initialization ：

#define DS1302_UNLOCK   write_ds1302(0x8e, 0x00);
#define DS1302_LOCK     write_ds1302(0x8e, 0x80);

void rtc_time_init(void)
{
    uint8_t hour;
    uint8_t hour_24 = 0;
    if (read_ds1302(READ_FLAG_ADDR) != RTC_INIT_FLAG)
    {
        write_ds1302(0x84, hour_24);
        set_rtc(init_time);
        return;
    }
    hour = read_ds1302(0x85);
    if (hour > 0x80)
    {
        // 12 The hour system is changed to 24 hourly 
        hour_24 = (hour > 0xA0)?(hour&0x1F)|DEC2BCD(12):(hour&0x1F);
        write_ds1302(0x84, hour_24);
    }
}

Read write interface ：

static void spi_rtc_send_byte(uint8_t byte)
{
    /* loop while data register in not empty */
    while(RESET == spi_i2s_flag_get(CURRENT_SPI, SPI_FLAG_TBE));
    /* send byte through the SPI peripheral */
    spi_i2s_data_transmit(CURRENT_SPI, byte);    
    while(spi_i2s_flag_get(CURRENT_SPI, SPI_FLAG_TRANS));
}

static void write_ds1302(uint8_t address, uint8_t data)     
{
    WRITE_MODE;
    CE_HIGH;
    spi_rtc_send_byte(address);
    spi_rtc_send_byte(data);
    CE_LOW;
}

static uint8_t read_ds1302(uint8_t address)
{
  uint8_t data;

    /* send addr */
    WRITE_MODE;
    CE_HIGH;
    spi_rtc_send_byte(address);

    /* recive data */
    READ_MODE;
    while(RESET == spi_i2s_flag_get(CURRENT_SPI, SPI_FLAG_RBNE));
    CE_LOW;
    WRITE_MODE;
    data = spi_i2s_data_receive(CURRENT_SPI);
    while(spi_i2s_flag_get(CURRENT_SPI, SPI_FLAG_TRANS));

    return data;
}

void set_rtc(time_t t)
{
    uint8_t year = t.year - YEAR_BASE;
    if(year >= 100) year = 0; 

    DS1302_UNLOCK;

    /*  Write the time stamp that has been set  */
    write_ds1302(WRITE_FLAG_ADDR, RTC_INIT_FLAG);
    write_ds1302(0x80, DEC2BCD(t.second));
    write_ds1302(0x82, DEC2BCD(t.minute));
    write_ds1302(0x84, DEC2BCD(t.hour));
    write_ds1302(0x86, DEC2BCD(t.day));
    write_ds1302(0x88, DEC2BCD(t.month));
    write_ds1302(0x8c, DEC2BCD(year));
    write_ds1302(0x8a, DEC2BCD(t.week));

    DS1302_LOCK;
}

time_t get_rtc(void)
{
    time_t t;
    uint16_t year = read_ds1302(0x8d);
    uint8_t  month = read_ds1302(0x89);
    uint8_t  day = read_ds1302(0x87);
    uint8_t  hour = read_ds1302(0x85);
    uint8_t  minute = read_ds1302(0x83);
    uint8_t second = read_ds1302(0x81);
    uint8_t  week = read_ds1302(0x8b);

    t.year = BCD2DEC(year) + YEAR_BASE;
    t.month = BCD2DEC(month);
    t.day = BCD2DEC(day);
    t.hour = BCD2DEC(hour);
    t.minute = BCD2DEC(minute);
    t.second = BCD2DEC(second);
    t.week = BCD2DEC(week);

 return t;
}

test result

DS1302 week （ register 0x8B） Of SPI wave form ：

DS1302 week （ register 0x8B）

Serial data ：