Allen 先楫資深 FAE

8年產品研發經驗，具有變頻器、PLC等工業產品開發經驗，也參與過汽車儀表、中控屏等車載產品的研發工作。在產品底層驅動、伺服驅動器、顯示儀表等領域有著豐富開發經驗。

在嵌入式產品應用開發中，經常需要MCU芯片產生任意的方波信號，從而驅動外設執行相應的操作。比如，驅動模擬量芯片、miniLED屏等。不同于PWM波這種占空比固定的信號，這些驅動信號往往是由等寬的高低電平任意排列的方波。

傳統的GPIO模擬方波時序，不僅占用CPU資源，而且波形的脈寬較大。在驅動miniLED屏這類外設時，達不到系統的功能要求。先楫半導體的全系列MCU可以將內存中的數據通過DMA來設置GPIO的電平，以TRGM互聯管理器和PWM比較器配合使用來設置脈沖寬度，從而產生任意時序的方波信號。該方案基于硬件方式來實現，不會占用CPU處理時間，波形寬度可達到50ns。下面介紹該方案的實現過程，例程基于HPM6360EVK實現。

定義波形數據

定義數組如下所示，其中32位無符號整數可以映射32個GPIO，每個數據位對應一個管腳。數組長度4096對應4096個方波周期。

ATTR_PLACE_AT_NONCACHEABLE_WITH_ALIGNMENT(8) uint32_t g_u32LedBufForGpio32[4096] = {0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0};

初始化GPIO管腳

此處將24個GPIO配置為輸出模式。

static void zh_led_gpio_config(void)
{
uint32_t pad_ctl = IOC_PAD_PAD_CTL_PE_SET(1) | IOC_PAD_PAD_CTL_PS_SET(1);

HPM_IOC->PAD[IOC_PAD_PC00].FUNC_CTL = IOC_PC00_FUNC_CTL_GPIO_C_00;
HPM_IOC->PAD[IOC_PAD_PC00].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC01].FUNC_CTL = IOC_PC01_FUNC_CTL_GPIO_C_01;
HPM_IOC->PAD[IOC_PAD_PC01].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC02].FUNC_CTL = IOC_PC02_FUNC_CTL_GPIO_C_02;
HPM_IOC->PAD[IOC_PAD_PC02].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC03].FUNC_CTL = IOC_PC03_FUNC_CTL_GPIO_C_03;
HPM_IOC->PAD[IOC_PAD_PC03].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC04].FUNC_CTL = IOC_PC04_FUNC_CTL_GPIO_C_04;
HPM_IOC->PAD[IOC_PAD_PC04].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC05].FUNC_CTL = IOC_PC05_FUNC_CTL_GPIO_C_05;
HPM_IOC->PAD[IOC_PAD_PC05].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC06].FUNC_CTL = IOC_PC06_FUNC_CTL_GPIO_C_06;
HPM_IOC->PAD[IOC_PAD_PC06].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC07].FUNC_CTL = IOC_PC07_FUNC_CTL_GPIO_C_07;
HPM_IOC->PAD[IOC_PAD_PC07].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC08].FUNC_CTL = IOC_PC08_FUNC_CTL_GPIO_C_08;
HPM_IOC->PAD[IOC_PAD_PC08].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC09].FUNC_CTL = IOC_PC09_FUNC_CTL_GPIO_C_09;
HPM_IOC->PAD[IOC_PAD_PC09].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC10].FUNC_CTL = IOC_PC10_FUNC_CTL_GPIO_C_10;
HPM_IOC->PAD[IOC_PAD_PC10].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC11].FUNC_CTL = IOC_PC11_FUNC_CTL_GPIO_C_11;
HPM_IOC->PAD[IOC_PAD_PC11].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC12].FUNC_CTL = IOC_PC12_FUNC_CTL_GPIO_C_12;
HPM_IOC->PAD[IOC_PAD_PC12].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC13].FUNC_CTL = IOC_PC13_FUNC_CTL_GPIO_C_13;
HPM_IOC->PAD[IOC_PAD_PC13].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC14].FUNC_CTL = IOC_PC14_FUNC_CTL_GPIO_C_14;
HPM_IOC->PAD[IOC_PAD_PC14].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC15].FUNC_CTL = IOC_PC15_FUNC_CTL_GPIO_C_15;
HPM_IOC->PAD[IOC_PAD_PC15].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC16].FUNC_CTL = IOC_PC16_FUNC_CTL_GPIO_C_16;
HPM_IOC->PAD[IOC_PAD_PC16].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC17].FUNC_CTL = IOC_PC17_FUNC_CTL_GPIO_C_17;
HPM_IOC->PAD[IOC_PAD_PC17].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC18].FUNC_CTL = IOC_PC18_FUNC_CTL_GPIO_C_18;
HPM_IOC->PAD[IOC_PAD_PC18].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC19].FUNC_CTL = IOC_PC19_FUNC_CTL_GPIO_C_19;
HPM_IOC->PAD[IOC_PAD_PC19].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC20].FUNC_CTL = IOC_PC20_FUNC_CTL_GPIO_C_20;
HPM_IOC->PAD[IOC_PAD_PC20].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC21].FUNC_CTL = IOC_PC21_FUNC_CTL_GPIO_C_21;
HPM_IOC->PAD[IOC_PAD_PC21].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC22].FUNC_CTL = IOC_PC22_FUNC_CTL_GPIO_C_22;
HPM_IOC->PAD[IOC_PAD_PC22].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC23].FUNC_CTL = IOC_PC23_FUNC_CTL_GPIO_C_23;
HPM_IOC->PAD[IOC_PAD_PC23].PAD_CTL = pad_ctl;

HPM_IOC->PAD[IOC_PAD_PC24].FUNC_CTL = IOC_PC24_FUNC_CTL_GPIO_C_24;
HPM_IOC->PAD[IOC_PAD_PC24].PAD_CTL = pad_ctl;

for(int i=0; i<24; i++) {
gpio_set_pin_output(HPM_GPIO0, GPIO_DO_GPIOC, i);
gpio_write_pin(HPM_GPIO0, GPIO_DO_GPIOC, i, 0);
}
}

配置DMA

在每次輸出波形之前都要進行一下DMA的設置，用戶通過調整波形數組的數據來設置想要的波形。DMA將數組的數據不斷搬運到DO[VALUE]寄存器中，因此要注意GPIO管腳和數組數據的對應關系。例程是輸出占空比為50%的PWM波。

static void zh_led_dma_config(void)
{
dma_channel_config_t ch_config = { 0 };
unsigned int i = 0;

for(i = 0;i<4096;i++)
{
g_u32LedBufForGpio32[i] = (i&1)?(~0):(0);
//g_u32LedBufForGpio32[i] = ~0;
//if(i%5 == 0)
//{
// g_u32LedBufForGpio32[i] = ~0;
//}
//else
//{
// g_u32LedBufForGpio32[i] = 0;
//}
}

dma_reset(HPM_HDMA);

intc_m_enable_irq_with_priority(BOARD_APP_HDMA_IRQ, 1);

dma_default_channel_config(HPM_HDMA, &ch_config);

ch_config.src_addr = (uint32_t)&g_u32LedBufForGpio32[0];

ch_config.dst_addr = (uint32_t)&HPM_GPIO0->DO[GPIO_DO_GPIOC].VALUE;
ch_config.src_width = DMA_TRANSFER_WIDTH_WORD; // 32位
ch_config.dst_width = DMA_TRANSFER_WIDTH_WORD; // 32位
ch_config.src_addr_ctrl = DMA_ADDRESS_CONTROL_INCREMENT;
ch_config.dst_addr_ctrl = DMA_ADDRESS_CONTROL_FIXED;
ch_config.size_in_byte = sizeof(g_u32LedBufForGpio32); //32 * sizeof(uint32_t);
ch_config.dst_mode = DMA_HANDSHAKE_MODE_NORMAL;
ch_config.src_burst_size = 0;

if (status_success != dma_setup_channel(HPM_HDMA, 0, &ch_config, false))
{
printf(" dma setup channel failed\n");
return;
}

dmamux_config(HPM_DMAMUX, DMAMUX_MUXCFG_HDMA_MUX0, HPM_DMA_SRC_MOT0_0, false);

trgm_dma_request_config(HPM_TRGM0, 0, 18);

pwm_enable_dma_request(HPM_PWM0, PWM_IRQ_CMP(18));

synt_enable_counter(HPM_SYNT, true);
pwm_start_counter(HPM_PWM0);
dmamux_enable_channel(HPM_DMAMUX, DMAMUX_MUXCFG_HDMA_MUX0);
dma_enable_channel(HPM_HDMA, 0);
}

設置DMA中斷，在輸出波形結束以后會觸發中斷響應函數。

void isr_dma(void)
{
uint32_t stat;

stat = dma_check_transfer_status(HPM_HDMA, 0);

if (0 != (stat & DMA_CHANNEL_STATUS_TC)) {
printf("Transfer done!");
}
}
SDK_DECLARE_EXT_ISR_M(BOARD_APP_HDMA_IRQ, isr_dma)

配置CLK時鐘

以PWM比較器產生需要的波形周期。

/**
* u8Phase from 1~18, 其中設置1 == 設置18, 設置1時 上升沿的邊與數據的開始時刻對齊，隨著設置的數字增大，上升沿的邊向右移動，設置8時，上升沿的邊大約在中間。
* */
static int zh_led_clk_config(uint8_t u8Phase)
{
pwm_cmp_config_t cmp_config_ch0[4] = {0};
pwm_config_t pwm_config = {0};
uint32_t u32CmpValue[4];

switch (u8Phase)
{
case 1:
u32CmpValue[0] = 6;
u32CmpValue[1] = 16;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 2:
u32CmpValue[0] = 7;
u32CmpValue[1] = 18;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 3:
u32CmpValue[0] = 17;
u32CmpValue[1] = 0;
u32CmpValue[2] = 18;
u32CmpValue[3] = 8;
break;
case 4:
u32CmpValue[0] = 17;
u32CmpValue[1] = 1;
u32CmpValue[2] = 18;
u32CmpValue[3] = 9;
break;
case 5:
u32CmpValue[0] = 17;
u32CmpValue[1] = 2;
u32CmpValue[2] = 18;
u32CmpValue[3] = 10;
break;
case 6:
u32CmpValue[0] = 17;
u32CmpValue[1] = 3;
u32CmpValue[2] = 18;
u32CmpValue[3] = 11;
break;
case 7:
u32CmpValue[0] = 17;
u32CmpValue[1] = 4;
u32CmpValue[2] = 18;
u32CmpValue[3] = 12;
break;
case 8:
u32CmpValue[0] = 17;
u32CmpValue[1] = 5;
u32CmpValue[2] = 18;
u32CmpValue[3] = 13;
break;
case 9:
u32CmpValue[0] = 17;
u32CmpValue[1] = 6;
u32CmpValue[2] = 18;
u32CmpValue[3] = 14;
break;
case 10:
u32CmpValue[0] = 18;
u32CmpValue[1] = 7;
u32CmpValue[2] = 17;
u32CmpValue[3] = 15;
break;
case 11:
u32CmpValue[0] = 18;
u32CmpValue[1] = 8;
u32CmpValue[2] = 17;
u32CmpValue[3] = 16;
break;
case 12:
u32CmpValue[0] = 17;
u32CmpValue[1] = 9;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 13:
u32CmpValue[0] = 0;
u32CmpValue[1] = 10;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 14:
u32CmpValue[0] = 1;
u32CmpValue[1] = 11;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 15:
u32CmpValue[0] = 2;
u32CmpValue[1] = 12;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 16:
u32CmpValue[0] = 3;
u32CmpValue[1] = 13;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 17:
u32CmpValue[0] = 4;
u32CmpValue[1] = 14;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
case 18:
u32CmpValue[0] = 5;
u32CmpValue[1] = 15;
u32CmpValue[2] = 18;
u32CmpValue[3] = 18;
break;
break;
default:
break;
}

pwm_stop_counter(HPM_PWM0);
pwm_set_reload(HPM_PWM0, 0, zh_led_PWM_FREQ-1);
pwm_set_start_count(HPM_PWM0, 0, 0);

pwm_config.enable_output = true;
pwm_config.invert_output = false;
pwm_config.update_trigger = pwm_shadow_register_update_on_modify;
pwm_config.fault_mode = pwm_fault_mode_force_output_highz;
pwm_config.fault_recovery_trigger = pwm_fault_recovery_on_fault_clear;
pwm_config.force_source = pwm_force_source_software;
pwm_config.dead_zone_in_half_cycle = 0;

/*cmp0 cmp1 cmp2 cmp3 for pwm ch0*/
cmp_config_ch0[0].cmp = u32CmpValue[0];
cmp_config_ch0[0].enable_ex_cmp = false;
cmp_config_ch0[0].mode = pwm_cmp_mode_output_compare;
cmp_config_ch0[0].update_trigger = pwm_shadow_register_update_on_hw_event;
cmp_config_ch0[0].ex_cmp = 0;
cmp_config_ch0[0].half_clock_cmp = 0;
cmp_config_ch0[0].jitter_cmp = 0;

cmp_config_ch0[1].cmp = u32CmpValue[1];
cmp_config_ch0[1].enable_ex_cmp = false;
cmp_config_ch0[1].mode = pwm_cmp_mode_output_compare;
cmp_config_ch0[1].update_trigger = pwm_shadow_register_update_on_hw_event;
cmp_config_ch0[1].ex_cmp = 0;
cmp_config_ch0[1].half_clock_cmp = 0;
cmp_config_ch0[1].jitter_cmp = 0;

cmp_config_ch0[2].cmp = u32CmpValue[2];
cmp_config_ch0[2].enable_ex_cmp = false;
cmp_config_ch0[2].mode = pwm_cmp_mode_output_compare;
cmp_config_ch0[2].update_trigger = pwm_shadow_register_update_on_hw_event;
cmp_config_ch0[2].ex_cmp = 0;
cmp_config_ch0[2].half_clock_cmp = 0;
cmp_config_ch0[2].jitter_cmp = 0;

cmp_config_ch0[3].cmp = u32CmpValue[3];
cmp_config_ch0[3].enable_ex_cmp = false;
cmp_config_ch0[3].mode = pwm_cmp_mode_output_compare;
cmp_config_ch0[3].update_trigger = pwm_shadow_register_update_on_hw_event;
cmp_config_ch0[3].ex_cmp = 0;
cmp_config_ch0[3].half_clock_cmp = 0;
cmp_config_ch0[3].jitter_cmp = 0;
if (status_success != pwm_setup_waveform(HPM_PWM0, 1, &pwm_config, 0, cmp_config_ch0, 4)) {
printf("failed to setup waveform for ch0\n");
return status_fail;
}

cmp_config_ch0[0].cmp = zh_led_PWM_FREQ-1;
cmp_config_ch0[0].update_trigger = pwm_shadow_register_update_on_modify;
pwm_load_cmp_shadow_on_match(HPM_PWM0, 4, &cmp_config_ch0[0]);

pwm_issue_shadow_register_lock_event(HPM_PWM0);

/* enable pwm fault protect */
pwm_fault_source_config_t config;
//config.external_fault_active_low = false;
config.source_mask = PWM_GCR_FAULTI0EN_MASK;
config.fault_recover_at_rising_edge = false;
config.fault_output_recovery_trigger = 0;
pwm_config_fault_source(HPM_PWM0, &config);


return status_success;
}

配置TRGM互聯管理器

互聯管理器TRGM以PWM的周期來觸發DMA進行數據搬運。

static void zh_led_trgm_config(void)
{
trgm_output_t stTrgmOutput;

stTrgmOutput.invert = false;
stTrgmOutput.type = trgm_output_same_as_input;

stTrgmOutput.input = 44;
trgm_output_config(HPM_TRGM0, 14, &stTrgmOutput);

pwm_enable_reload_at_synci(HPM_PWM0);

synt_reset_counter(HPM_SYNT);
synt_set_reload(HPM_SYNT, zh_led_PWM_FREQ-1);
synt_set_comparator(HPM_SYNT, 0, zh_led_PWM_FREQ-1);
}

測試程序如下：

int main(void)
{
unsigned int j=3;
board_init();
zh_led_gpio_config();
zh_led_clk_config(2);
zh_led_trgm_config();
zh_led_dma_config();

printf("start\n");

while(j--)
{
printf("j = %d\n", j);

zh_led_dma_config();
pwm_start_counter(HPM_PWM0);

board_delay_ms(500);
};

printf("stop\n");

while(1);

return 0;
}

串口打印結果如下：

測量GPIO的波形：

因為HDMA訪問AHB SRAM速度更快，可以將數據存儲到AHB SRAM來提高刷新速度。

__attribute__ ((section(".ahb_sram"))) uint32_t g_u32LedBufForGpio32[1024]={0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0, 0xFFFFFFFF, 0};

使用邏輯分析儀測試波形如下：

用示波器測量波形如下圖所示，信號質量表現優異。