Generating sine wave on STM32F3 with DMA - garbled output

Question

I am trying to generate a waveform using a const table, DMA and DAC.

This is the STM32F303VCT on a Discovery F3 board.

I am using libopencm3 , but I hope you'll clearly see what is happening - it's all just functions to set the control registers.

#define SINE_TABLE_LEN 256

static const uint16_t sine_table[] = {
    2047, 2097, 2147, 2198, 2248, 2298, 2347, 2397, 2446, 2496, 2544, 2593, 2641, 2689, 2737, 2784, 2830, 2877, 2922, 2967, 3012, 3056, 3099, 3142, 3184, 3226, 3266, 3306, 3346, 3384, 3422, 3458, 3494, 3530, 3564, 3597, 3629, 3661, 3691, 3721, 3749, 3776, 3803, 3828, 3852, 3875, 3897, 3918, 3938, 3957, 3974, 3991, 4006, 4020, 4033, 4044, 4055, 4064, 4072, 4079, 4084, 4088, 4092, 4093, 4094, 4093, 4092, 4088, 4084, 4079, 4072, 4064, 4055, 4044, 4033, 4020, 4006, 3991, 3974, 3957, 3938, 3918, 3897, 3875, 3852, 3828, 3803, 3776, 3749, 3721, 3691, 3661, 3629, 3597, 3564, 3530, 3494, 3458, 3422, 3384, 3346, 3306, 3266, 3226, 3184, 3142, 3099, 3056, 3012, 2967, 2922, 2877, 2830, 2784, 2737, 2689, 2641, 2593, 2544, 2496, 2446, 2397, 2347, 2298, 2248, 2198, 2147, 2097, 2047, 1997, 1947, 1896, 1846, 1796, 1747, 1697, 1648, 1598, 1550, 1501, 1453, 1405, 1357, 1310, 1264, 1217, 1172, 1127, 1082, 1038, 995, 952, 910, 868, 828, 788, 748, 710, 672, 636, 600, 564, 530, 497, 465, 433, 403, 373, 345, 318, 291, 266, 242, 219, 197, 176, 156, 137, 120, 103, 88, 74, 61, 50, 39, 30, 22, 15, 10, 6, 2, 1, 0, 1, 2, 6, 10, 15, 22, 30, 39, 50, 61, 74, 88, 103, 120, 137, 156, 176, 197, 219, 242, 266, 291, 318, 345, 373, 403, 433, 465, 497, 530, 564, 600, 636, 672, 710, 748, 788, 828, 868, 910, 952, 995, 1038, 1082, 1127, 1172, 1217, 1264, 1310, 1357, 1405, 1453, 1501, 1550, 1598, 1648, 1697, 1747, 1796, 1846, 1896, 1947, 1997
//  0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, 240, 256, 272, 288, 304, 320, 336, 352, 368, 384, 400, 416, 432, 448, 464, 480, 496, 512, 528, 544, 560, 576, 592, 608, 624, 640, 656, 672, 688, 704, 720, 736, 752, 768, 784, 800, 816, 832, 848, 864, 880, 896, 912, 928, 944, 960, 976, 992, 1008, 1024, 1040, 1056, 1072, 1088, 1104, 1120, 1136, 1152, 1168, 1184, 1200, 1216, 1232, 1248, 1264, 1280, 1296, 1312, 1328, 1344, 1360, 1376, 1392, 1408, 1424, 1440, 1456, 1472, 1488, 1504, 1520, 1536, 1552, 1568, 1584, 1600, 1616, 1632, 1648, 1664, 1680, 1696, 1712, 1728, 1744, 1760, 1776, 1792, 1808, 1824, 1840, 1856, 1872, 1888, 1904, 1920, 1936, 1952, 1968, 1984, 2000, 2016, 2032, 2048, 2063, 2079, 2095, 2111, 2127, 2143, 2159, 2175, 2191, 2207, 2223, 2239, 2255, 2271, 2287, 2303, 2319, 2335, 2351, 2367, 2383, 2399, 2415, 2431, 2447, 2463, 2479, 2495, 2511, 2527, 2543, 2559, 2575, 2591, 2607, 2623, 2639, 2655, 2671, 2687, 2703, 2719, 2735, 2751, 2767, 2783, 2799, 2815, 2831, 2847, 2863, 2879, 2895, 2911, 2927, 2943, 2959, 2975, 2991, 3007, 3023, 3039, 3055, 3071, 3087, 3103, 3119, 3135, 3151, 3167, 3183, 3199, 3215, 3231, 3247, 3263, 3279, 3295, 3311, 3327, 3343, 3359, 3375, 3391, 3407, 3423, 3439, 3455, 3471, 3487, 3503, 3519, 3535, 3551, 3567, 3583, 3599, 3615, 3631, 3647, 3663, 3679, 3695, 3711, 3727, 3743, 3759, 3775, 3791, 3807, 3823, 3839, 3855, 3871, 3887, 3903, 3919, 3935, 3951, 3967, 3983, 3999, 4015, 4031, 4047, 4063, 4079
};    

void send_dac_sine()
{
    const uint32_t dma = DMA2;
    const uint32_t ch = DMA_CHANNEL3;

    dac_dma_disable(CHANNEL_1);
    dma_disable_channel(dma, ch);
    dma_channel_reset(dma, ch);

    // DMA config
    dma_enable_circular_mode(dma, ch);

    dma_set_peripheral_address(dma, ch, (uint32_t) &DAC_DHR12R1);
    dma_set_memory_address(dma, ch, (uint32_t) sine_table);

    dma_set_memory_size(dma, ch, DMA_CCR_MSIZE_16BIT); // uint16_t
    dma_set_peripheral_size(dma, ch, DMA_CCR_MSIZE_32BIT); // 32-bit register
    dma_set_number_of_data(dma, ch, SINE_TABLE_LEN);
    dma_enable_memory_increment_mode(dma, ch); // incr mem. addr
    dma_disable_peripheral_increment_mode(dma, ch); // keep periph addr
    dma_set_read_from_memory(dma, ch); // memory -> periph

    dma_set_priority(dma, ch, DMA_CCR_PL_VERY_HIGH);

    // launch

    dac_dma_enable(CHANNEL_1); // enable the DAC to send DMA requests
    dma_enable_channel(dma, ch);
}

The DAC is triggered by TIMER6 TRGO.

I think I must have some bug in the table definition or the table memory address.

The DMA is running, I can see something sent to the DAC.

However, it is not my table - here's it plotted, as captured by an ADC:

What could be wrong?

ps. if I let it run longer, I get something this (it's periodic)

Answer 1

The whole problem was one wrong letter in a constant identifier. Duuuh

Peripheral size is specified with DMA_CCR_PSIZE_* , not DMA_CCR_MSIZE_* .

Also I messed up the pointers / addresses...

Full, working code:

#define SINE_TABLE_LEN 256
const uint16_t sine_table[SINE_TABLE_LEN] = { // now with actual sine
    2047, 2097, 2147, 2198, 2248, 2298, 2347, 2397, 2446, 2496, 2544, 2593, 2641, 2689, 2737, 2784, 2830, 2877, 2922, 2967, 3012, 3056, 3099, 3142, 3184, 3226, 3266, 3306, 3346, 3384, 3422, 3458, 3494, 3530, 3564, 3597, 3629, 3661, 3691, 3721, 3749, 3776, 3803, 3828, 3852, 3875, 3897, 3918, 3938, 3957, 3974, 3991, 4006, 4020, 4033, 4044, 4055, 4064, 4072, 4079, 4084, 4088, 4092, 4093, 4094, 4093, 4092, 4088, 4084, 4079, 4072, 4064, 4055, 4044, 4033, 4020, 4006, 3991, 3974, 3957, 3938, 3918, 3897, 3875, 3852, 3828, 3803, 3776, 3749, 3721, 3691, 3661, 3629, 3597, 3564, 3530, 3494, 3458, 3422, 3384, 3346, 3306, 3266, 3226, 3184, 3142, 3099, 3056, 3012, 2967, 2922, 2877, 2830, 2784, 2737, 2689, 2641, 2593, 2544, 2496, 2446, 2397, 2347, 2298, 2248, 2198, 2147, 2097, 2047, 1997, 1947, 1896, 1846, 1796, 1747, 1697, 1648, 1598, 1550, 1501, 1453, 1405, 1357, 1310, 1264, 1217, 1172, 1127, 1082, 1038, 995, 952, 910, 868, 828, 788, 748, 710, 672, 636, 600, 564, 530, 497, 465, 433, 403, 373, 345, 318, 291, 266, 242, 219, 197, 176, 156, 137, 120, 103, 88, 74, 61, 50, 39, 30, 22, 15, 10, 6, 2, 1, 0, 1, 2, 6, 10, 15, 22, 30, 39, 50, 61, 74, 88, 103, 120, 137, 156, 176, 197, 219, 242, 266, 291, 318, 345, 373, 403, 433, 465, 497, 530, 564, 600, 636, 672, 710, 748, 788, 828, 868, 910, 952, 995, 1038, 1082, 1127, 1172, 1217, 1264, 1310, 1357, 1405, 1453, 1501, 1550, 1598, 1648, 1697, 1747, 1796, 1846, 1896, 1947, 1997
};

void send_dac_sine()
{
    const uint32_t dma = DMA2;
    const uint32_t ch = DMA_CHANNEL3;

    dac_set_waveform_generation(DAC_CR_WAVE1_DIS);
    dac_dma_disable(CHANNEL_1);
    dma_disable_channel(dma, ch);
    dma_channel_reset(dma, ch);

    dma_enable_circular_mode(dma, ch);
    dma_set_peripheral_address(dma, ch, (uint32_t) &DAC_DHR12R1);
    dma_set_memory_address(dma, ch, (uint32_t) &sine_table);
    dma_set_memory_size(dma, ch, DMA_CCR_MSIZE_16BIT);
    dma_set_peripheral_size(dma, ch, DMA_CCR_PSIZE_16BIT);
    dma_set_read_from_memory(dma, ch);
    dma_set_number_of_data(dma, ch, SINE_TABLE_LEN);

    dma_set_priority(dma, ch, DMA_CCR_PL_VERY_HIGH);

    dma_enable_memory_increment_mode(dma, ch);
    dma_disable_peripheral_increment_mode(dma, ch);

    dac_dma_enable(CHANNEL_1);
    dma_enable_channel(dma, ch);
}

Answer 2

have you tried to memcpy it somewhere? it might have something to do with it being static, ie. not on the normal stack. just a thought...