好久也没跑例程了。原因是板子坏了，怎么好得请看：SAM4N XPLAINED pro出现 No device detect性ed. Error 4109的解决办法
今天跑的是ADC例程：
在Atmel Studio6.2环境下插上SAM4N板子，就直接有打开新例程，那一项。然后打开ADC的那个例程，截图如下：
其中ADC软出管脚定义如下：
- #ifndef CONF_DACC_SINEWAVE_EXAMPLE_H_INCLUDED
- #define CONF_DACC_SINEWAVE_EXAMPLE_H_INCLUDED
- //! DAC channel used for test (PB13)
- #define DACC_CHANNEL 0
- //! DAC register base for test
- #define DACC_BASE DACC
- //! DAC ID for test
- #define DACC_ID ID_DACC
- #endif /* CONF_DACC_SINEWAVE_EXAMPLE_H_INCLUDED */
也就是说用的是DAC通道0即第PB13脚输出。
而该程可以允许用户输入频率的大小，及幅度的大小，当然在一定范围内。其值的改变是在时钟中断里实现的
- void SysTick_Handler(void)
- {
- uint32_t status;
- uint32_t dac_val;
- status = dacc_get_interrupt_status(DACC_BASE);
- /* If ready for new data */
- if ((status & DACC_ISR_TXRDY) == DACC_ISR_TXRDY) {
- g_ul_index_sample++;
- if (g_ul_index_sample >= SAMPLES) {
- g_ul_index_sample = 0;
- }
- dac_val = g_uc_wave_sel ?
- ((g_ul_index_sample > SAMPLES / 2) ? 0 : MAX_AMPLITUDE)
- : wave_to_dacc(gc_us_sine_data[g_ul_index_sample],
- g_l_amplitude,
- MAX_DIGITAL * 2, MAX_AMPLITUDE);
- dacc_write_conversion_data(DACC_BASE, dac_val);
- }
- }
而主程序负责同用户交互：
- while (1) {
- usart_serial_getchar((Usart *)CONSOLE_UART, &uc_key);
- switch (uc_key) {
- case '0':
- printf("Frequency:\t");
- ul_freq = get_input_value(MIN_FREQUENCY, MAX_FREQUENCY);
- printf("\r\n");
- if (ul_freq != VAL_INVALID) {
- printf("Set frequency to : %luHz\n\r", (unsigned long)ul_freq);
- SysTick_Config(sysclk_get_cpu_hz() / (ul_freq * SAMPLES));
- g_ul_frequency = ul_freq;
- }
- break;
- case '1':
- printf("Amplitude:\t");
- ul_amp = get_input_value(MIN_AMPLITUDE, MAX_AMPLITUDE);
- printf("\r\n");
- if (ul_amp != VAL_INVALID) {
- printf("Set amplitude to : %lu\n\r", (unsigned long)ul_amp);
- g_l_amplitude = ul_amp;
- }
- break;
- case 'i':
- case 'I':
- printf("-I- Frequency : %lu Hz Amplitude : %ld\n\r",
- (unsigned long)g_ul_frequency, (long)g_l_amplitude);
- break;
- case 'w':
- case 'W':
- printf("-I- Switch wave to : %s\n\r", g_uc_wave_sel ?
- "SINE" : "Full Amplitude SQUARE");
- g_uc_wave_sel = (g_uc_wave_sel + 1) & 1;
- break;
- case 'm':
- case 'M':
- display_menu();
- break;
- }
- puts("Press \'m\' or \'M\' to display the main menu again!\r");
- }
以下是运行的载图：有关输出示波器的照片明天再发，今天手机没有拿。
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楼主
