1簡介

本文主要介紹基于HPM6750 EVK Mini板驅(qū)動點(diǎn)亮LED三色燈，從而讓用戶能快速熟悉先楫MCU PWM定時器原理和HPM_SDK Driver API的使用方法。

本文檔中有關(guān)HPM6750 EVK mini板的使用說明可以參考位于SDK軟件包中\(zhòng)Doc目錄下的HPM6750EVKMINI_UG.pdf。

本文檔中有關(guān)HPM6750 EVK mini 硬件原理圖，請查閱HPM6750EVKMINI硬件設(shè)計資料\原理圖\HPM6750EVKMINI Rev.B.pdf。

本文檔中有關(guān)HPM6750 MCU datasheet，請查閱HPM6750_DS.pdf；有關(guān)HPM6750 MCU user manual請查閱HPM6750_UM.pdf。

本文將基于HPM SDK中pwm driver api接口抽象封裝針對LED燈的adapte接口，并通過adapte接口實現(xiàn)LED三色燈的開關(guān)和呼吸效果。

2 環(huán)境準(zhǔn)備

2.1PWM定時器原理

查閱HPM6750 MCU user manual文檔中章節(jié)：電機(jī)系統(tǒng)->45 PWM定時器PWM內(nèi)容。

PWM的框圖

大致介紹：

l 先楫PWM定時器由4個模塊組成：定時器時間基準(zhǔn)模塊、比較器模塊、輸出通道模塊、PWM輸出控制模塊。

l 定時器時間基準(zhǔn)模塊決定PWM定時器運(yùn)行的時間和周期。通過讀寫計數(shù)器、起始寄存器、重載寄存器、計數(shù)器使能來設(shè)置定時器時間基準(zhǔn)模塊。

l PWM生成通過定時器時間基準(zhǔn)模塊配合比較器以及輸出通道來生成輸出參考信號。一個輸出通道可匹配多個比較器(注意：匹配多個比較器必須連續(xù))，當(dāng)計數(shù)器的值等于比較器的值時，產(chǎn)生匹配事件邏輯1，當(dāng)計數(shù)器到達(dá)重載數(shù)值時，產(chǎn)生重載事件邏輯0。如果比較器的值和重載值相同，則會保持邏輯1產(chǎn)生100%占空比輸出，如果比較器的值>重載值，則會保持邏輯0產(chǎn)生0%占空比輸出。

l 輸出通道輸出的參考信號經(jīng)過PWM輸出控制模塊處理互補(bǔ)控制、死區(qū)插入、取反控制、強(qiáng)制輸出、故障保護(hù)后，形成輸出信號到IO口。如果不對輸出控制模塊操作則透傳輸出通道參考信號。由于LED RGB三色燈使用不到以上，本文檔不介紹PWM輸出控制模塊。

l 針對LED 簡單的PWM波形，只需要一個比較器即可實現(xiàn)。波形實現(xiàn)如圖：

波形實現(xiàn)如圖

PWM頻率：總線時鐘頻率/重載值。

占空比：比較器值/總步長 * 100。

2.2PWM Driver API梳理

查閱HPM SDK軟件API手冊中PWM driver APIs章節(jié)。

針對LED 簡單波形使用到的接口有：

//重載值設(shè)置pwm_set_reload//計數(shù)器起始值設(shè)置pwm_set_start_count//比較器配置pwm_config_cmp//PWM波形設(shè)置(輸出通道和比較器匹配設(shè)置)pwm_setup_waveform//加載比較器影子寄存器匹配設(shè)置
pwm_load_cmp_shadow_on_match//計時器使能計數(shù)pwm_start_counter//計數(shù)器禁止計數(shù)pwm_stop_counter//更新比較器邊沿觸發(fā)值(調(diào)整占空比)pwm_update_raw_cmp_edge_aligned//使能PWM通道輸出pwm_enable_output
//禁止PWM通道輸出pwm_disable_output

2.3確認(rèn)LED 硬件PIN腳

查閱HPM6750 EVK mini 硬件原理圖，確認(rèn)LED三色燈三路PWM通道和管腳，分別為：

RED: PWM0.P7 —— PB20

GREEN: PWM1.P1 —— PB18

BLUE: PWM1.P0 —— PB19

3 接口封裝

3.1PWM初始化

pwm_port_handle_t hpm_pwm_init(PWM_Type* pwm_id, uint32_t pwm_out, uint32_t pwm_cmp, bool init_zero, clock_name_t clock_name){ led_pwm_t *handle = malloc(sizeof(led_pwm_t)); if(NULL == handle) return NULL; memset(handle, 0, sizeof(led_pwm_t)); handle->pwm = pwm_id; handle->reload = 0; handle->step = 0; handle->pwm_irq = 0; handle->pwm_cmp = pwm_cmp; handle->pwm_ch = pwm_out; handle->pwm_cmp_initial_zero = init_zero; handle->bus_freq = clock_get_frequency(clock_name); return (pwm_port_handle_t)handle;}

handle->pwm_irq = 0; handle->pwm_cmp = pwm_cmp; handle->pwm_ch = pwm_out; handle->pwm_cmp_initial_zero = init_zero; handle->bus_freq = clock_get_frequency(clock_name); return (pwm_port_handle_t)handle;

3.2PWM釋放

void hpm_pwm_deinit(pwm_port_handle_t pwm_handle){ led_pwm_t *handle = (led_pwm_t *)pwm_handle; if(NULL == handle) return; pwm_disable_output(handle->pwm, handle->pwm_ch); free(handle); handle = NULL; return;

3.3PWM運(yùn)行

#define PWM_DUTY_STEP_COUNT (100U)/*duty: 0~100%, freq: 100~200000000*/int hpm_pwm_start(pwm_port_handle_t pwm_handle, uint32_t duty, uint32_t freq){ led_pwm_t *handle = (led_pwm_t *)pwm_handle; uint32_t reload, now_cmp; pwm_cmp_config_t cmp_config = {0}; pwm_config_t pwm_config = {0}; if(NULL == handle) { return -1; } if(freq > handle->bus_freq) { return -2; } reload = handle->bus_freq / freq - 1; //start 0 index if(reload == 0) return -2; if(reload != handle->reload || handle->reload == 0) { handle->reload = reload; pwm_stop_counter(handle->pwm); pwm_get_default_pwm_config(handle->pwm, &pwm_config); pwm_get_default_cmp_config(handle->pwm, &cmp_config); pwm_config.enable_output = false; pwm_config.dead_zone_in_half_cycle = 0; pwm_config.invert_output = false; /* * reload and start counter */ pwm_set_reload(handle->pwm, 0, handle->reload); pwm_set_start_count(handle->pwm, 0, 0); cmp_config.mode = pwm_cmp_mode_output_compare; cmp_config.cmp = handle->pwm_cmp_initial_zero ? 0 : handle->reload + 1; cmp_config.update_trigger = pwm_shadow_register_update_on_modify; /* config initial compare value which should take affect immediately */ pwm_config_cmp(handle->pwm, handle->pwm_cmp, &cmp_config); /* * config pwm as output driven by cmp */ if (status_success != pwm_setup_waveform(handle->pwm, handle->pwm_ch, &pwm_config, handle->pwm_cmp, &cmp_config, 1)) { printf("failed to setup waveform\n"); return -3; } pwm_load_cmp_shadow_on_match(handle->pwm, handle->pwm_cmp, &cmp_config); handle->step = (handle->reload + 1)/PWM_DUTY_STEP_COUNT; pwm_update_raw_cmp_edge_aligned(handle->pwm, handle->pwm_cmp, handle->pwm_cmp_initial_zero ? 0 : handle->reload + 1); pwm_start_counter(handle->pwm); } if(duty == 100) { now_cmp = handle->reload + 1; } else { now_cmp = handle->step * PWM_DUTY_STEP_COUNT/100 * duty; } pwm_update_raw_cmp_edge_aligned(handle->pwm, handle->pwm_cmp, now_cmp); pwm_enable_output(handle->pwm, handle->pwm_ch); return 0;

3.4PWM停止

nt hpm_pwm_stop(pwm_port_handle_t pwm_handle){ led_pwm_t *handle = (led_pwm_t *)pwm_handle; if(NULL == handle) return -1; pwm_disable_output(handle->pwm, handle->pwm_ch); return 0;

4 功能實現(xiàn)

4.1呼吸燈功能

#define LED_PWM_FREQ 200000 //200khz

int sample_breath_lamp(pwm_port_handle_t handle){ if(NULL == handle) { printf("handle is null\n"); return -1; } for(uint32_t i = 0; i <= 100; i++) { hpm_pwm_start(handle, i, LED_PWM_FREQ); board_delay_ms(10); } for(uint32_t i = 100; i > 0; i--) { hpm_pwm_start(handle, i, LED_PWM_FREQ); board_delay_ms(10); } hpm_pwm_stop(handle); return 0;}

4.2LED點(diǎn)亮呼吸

board_init(); board_init_rgb_pwm_pins(); printf("rgb led example\n"); pwm_port_handle_t red_handle = hpm_pwm_init(RED_PWM, RED_PWM_OUT, RED_PWM_CMP, RED_PWM_CMP_INITIAL_ZERO, RED_PWM_CLOCK_NAME); if(red_handle == NULL) { printf("red pwm init fail!\n"); while(1); } pwm_port_handle_t green_handle = hpm_pwm_init(GREEN_PWM, GREEN_PWM_OUT, GREEN_PWM_CMP, GREEN_PWM_CMP_INITIAL_ZERO, GREEN_PWM_CLOCK_NAME); if(green_handle == NULL) { printf("green pwm init fail!\n"); while(1); } pwm_port_handle_t blue_handle = hpm_pwm_init(BLUE_PWM, BLUE_PWM_OUT, BLUE_PWM_CMP, BLUE_PWM_CMP_INITIAL_ZERO, BLUE_PWM_CLOCK_NAME); if(blue_handle == NULL) { printf("blue pwm init fail!\n"); while(1); } //on led and off led hpm_pwm_start(red_handle, 100, LED_PWM_FREQ); board_delay_ms(1000); hpm_pwm_start(red_handle, 0, LED_PWM_FREQ); board_delay_ms(1000); hpm_pwm_start(green_handle, 100, LED_PWM_FREQ); board_delay_ms(1000); hpm_pwm_start(green_handle, 0, LED_PWM_FREQ); board_delay_ms(1000); hpm_pwm_start(blue_handle, 100, LED_PWM_FREQ); board_delay_ms(1000); hpm_pwm_start(blue_handle, 0, LED_PWM_FREQ); board_delay_ms(1000); while(1) { printf("now red breath...\n"); sample_breath_lamp(red_handle); printf("now green breath...\n"); sample_breath_lamp(green_handle); printf("now bule breath...\n"); sample_breath_lamp(blue_handle); } hpm_pwm_deinit(red_handle); hpm_pwm_deinit(green_handle); hpm_pwm_deinit(blue_handle); return 0;}

5 功能測試

5.1 生成rgb_led工程

工程路徑在HPM_SDK 文件夾:“hpm_sdk\samples\rgb_led”

根據(jù)SDK 開發(fā)指南文檔《HPM6750EVKMINI_UG》中的工程生成步驟，在rgb_led目錄下來生成segger embedded studio的工程文件。

通過雙擊工程文件multcore_core0.emProject可以直接進(jìn)入SES(segger embedded studio) 。

雙擊“multcore_core0.emProject”打開該工程，如下圖。

5.2 運(yùn)行rgb_led

運(yùn)行rgb_led例程，可以查看到Mini板三色點(diǎn)亮熄滅以及循環(huán)呼吸效果。

5.3PWM波形查看

通過示波器查看rgb pwm波形，確認(rèn)頻率和占空比是否正確。

A.200KHz，50%占空比

實測：一個周期5us，波峰2.495us。

B.200KHz, 20%占空比

實測：一個周期5us，波峰：994.7ns，驗證通過。

C.100KHz, 50%占空比

實測：一個周期10us，波峰4.995us，驗證通過。

D.100KHz, 10%占空比

實測：一個周期10us，波峰994.8ns，驗證通過。