[MSP430F5529 Review] 6. DMA & SPI driving WS2812B color dot matrix screen

wuguangtao · 2020-11-27 21:35 上传

[MSP430F5529 Review] 6. DMA & SPI driving WS2812B color dot matrix screen [Copy link]

<div class='showpostmsg'><i class="pstatus">This post was last edited by wuguangtao on 2020-11-27 21:41</i> # MSP430F5529 drives WS2812B LED Last time I used MAX7219 to drive a monochrome LED dot matrix screen. This time I changed to a cooler one, WS2812B LED dot matrix screen, full-color LED, single-line control, 5V power supply. Let's get started. ## WS2812B Here is the WS2812B color light screen I found, 8*8, a total of 64 full-color LEDs. 
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 WS2812B is a widely used LED light that can be used as colored lights, ribbons, colored balls, color screens, etc. Each LED contains 4 IO ports, and the LEDs can be cascaded and connected through DIN and DOUT to form a ribbon. The dot matrix screen is actually a variant of the ribbon, with an S-shaped distribution. 
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 | NO. | Symbol | Function description | | ---- | ------ | -------------------------- | | 1 | VDD | Power supply LED | | 2 | DOUT | Control data signal output | | 3 | VSS | Ground | | 4 | DIN | Control data signal input | ### Although the WS2812B timing has only one control line, it can control hundreds or thousands of LEDs, so its timing requirements are relatively strict. 
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 As shown in the figure above, each bit is determined by a high and low level, and about 1.25us represents a 0 or 1. The accuracy is at the us level. * 0 - T0H (0.4us) - T0L(0.85us) * 1 - T1H(0.85us) - T1L(0.4us) The color of each LED consists of 3 bytes, R, G, B, which is 24 bits. For a lamp, you only need to send 3 bytes and then delay for more than 50us to light it up. If there are multiple LEDs, such as 64, then you need to send 64*3 bytes of data continuously and then delay for more than 50us. 
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 **It should be noted that the sending order of RGB is GRB, starting with the G part, and the high bit first. ** After introducing the WS2812B lamp, let's see how to use MSP430F5529LP to drive it and achieve some interesting lighting effects. ## UCS The first thing to consider is the timing problem, which requires us level, so a high-frequency clock must be configured. It is just right to talk about the clock configuration of 5529 in detail here. 
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 MSP430F5529 mainly includes the first three clocks in the table above. The main system clock MCLK is usually used for CPU clk and is disabled in low power mode. SMCLK is a subsystem clock used to drive high-speed peripherals. It is enabled in LPM0 low power mode, but disabled in LPM3, LPM4, and LPM5 modes. ACLK is an auxiliary clock that drives low-speed peripherals. It is available in LPM3 mode and disabled in LPM4 and LPM5 modes. These clocks can be generated by the following 6 clock sources. | Source | Description | | ------ | --------------------------------------------------------------- | | DCO | digitally controlled oscillator | | FLL | frequency-locked loop | | REFO | This is a modestly precise low-power on-chip oscillator that does not require a crystal. It operates at 32 kHz. | | | VLO | This oscillator is not very precise but does not require a crystal and has the lowest power of the three. It usually operates somewhere between 12 kHz and 20 kHz. | | REFO is an internal medium-precision 32KHz clock source, usually used as the reference clock of FLL. The FLL is a frequency-locked loop, which can be used with the DCO to multiply and divide the frequency, thereby outputting a high-precision clock frequency. Finally, the XT1 and XT2 external crystal oscillators, in the MSP430F5529LP, XT1 is 32768Hz and XT2 is 4MHz. Their pin definitions are shown in the figure below: 
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 By default, XT1 and XT2 are not enabled, and you need to set the corresponding IO and select the multiplexing function. The following is the clock diagram provided by the official document. It can be seen that MCLK/SMCLK/ACLK can be generated in 6 ways: XT1CLK, VLOCLK, REFOCLK, DCOCLK, DCOCLKDIV, and XT2CLK. 
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 ### Select the clock For this experiment, we need to communicate through high-speed SPI. We can choose to use SMCLK. The clock source can be REFO or XT1/XT2 combined with FLL. According to the timing requirements of WS2812B, a switching frequency of 0.65us ~ 1.85us is required. If 16MHz SMCLK is used, the baud rate coefficient is set to 3. Each SPI transmission corresponds to 1 byte and requires about 3/16M * 8, which is about 1.5us.Meet the requirements. Then each transmitted byte contains 8 bits, but it is only used to represent 1 bit, `0b11110000` represents 1, and `0b11000000` represents 0, which perfectly solves the clock problem. The following is to use REFO as the reference clock according to the requirements, and obtain 16M MCLK and SMCLK through DCO and FLL division. ```c void init_ucs() { UCSCTL3 |= SELREF_2; // Set DCO FLL reference = REFO __bis_SR_register(SCG0); // Disable the FLL control loop UCSCTL0 = 0x0000; // Set lowest possible DCOx, MODx UCSCTL1 = DCORSEL_5; // Select DCO range 24MHz operation UCSCTL2 = FLLD_1 + 499; // Set DCO Multiplier for 12MHz // (N + 1) * FLLRef = Fdco // (499 + 1) * 32768 = 16MHz // Set FLL Div = fDCOCLK/2 __bic_SR_register(SCG0); // Enable the FLL control loop // Worst-case settling time for the DCO when the DCO range bits have been // changed is nx 32 x 32 x f_MCLK / f_FLL_reference. See UCS chapter in 5xx // UG for optimization. // 32 x 32 x 16 MHz / 32,768 Hz = 500000 = MCLK cycles for DCO to settle __delay_cycles(500000); } ``` ## SPI According to the above analysis, the baud rate coefficient of SPI is 3, using SMCLK, 3-pin master mode, and actually only one IO is used, which is `P3.0` ```c void init_spi() { P3SEL |= BIT0; // P3.0 SPI MOSI option select UCB0CTL1 |= UCSWRST; // **Put state machine in reset** UCB0CTL0 |= UCMST + UCCKPH + UCMSB + UCSYNC; // 3-pin, 8-bit SPI master, MSB UCB0CTL1 |= UCSSEL_2; // SMCLK source (16 MHz) UCB0BR0 = 0x03; // 16 MHz / 3 = .1875 us per bit UCB0BR1 = 0; // UCB0CTL1 &= ~UCSWRST; // Initialize USCI state machine } ``` ### Driving the WS2812B LED Now that the SPI is configured, it is easy to light up the LED. Use a structure to save the information of a single LED, in G\R\B order, initialized to all 0s, and then light up the LEDs one by one according to the number of LEDs. For each LED, send 3 sets of RGB values in a loop. The number of `UCB0TXBUF` to light up all LEDs is `NUM_LEDS * 3 * 8` ```C #define NUM_LEDS (64) // NUMBER OF LEDS IN YOUR MATRIX #define MATRIX_WIDTH (8) // Width of led matrix #define MATRIX_HEIGHT (8) // HEIGHT of led matrix // Transmit codes #define HIGH_CODE (0xF0) // b11110000 #define LOW_CODE (0xC0) // b11000000 // WS2812 takes GRB format typedef struct { uint8_t green; uint8_t red; uint8_t blue; } LED; LED leds[NUM_LEDS] = { { 0, 0, 0 } }; // Send colors to the matrix and show them. Disables interrupts while processing. void showMatrix() { __bic_SR_register(GIE); // disable interrupts // send RGB color for every LED unsigned int i, j; for (i = 0; i < NUM_LEDS; i++) { uint8_t *rgb = (uint8_t *)&leds<i>; // get GRB color for this LED // send green, then red, then blue for (j = 0; j < 3; j++) { uint8_t mask = 0x80; // b1000000 // check each of the 8 bits while (mask != 0) { while (!(UCB0IFG & UCTXIFG)); // wait to transmit if (rgb[j] & mask) { // most significant bit first UCB0TXBUF = HIGH_CODE; // send 1 } else { UCB0TXBUF = LOW_CODE; // send 0 } mask >>= 1; // check next bit } } } // send RES code for at least 50 us (800 cycles at 16 MHz) _delay_cycles(800); __bis_SR_register(GIE); // enable interrupts } ``` In this way, the simplest LED driver is completed. ## PMM One more thing to note is that for a large number of LEDs, the default voltage of MSP430 may not be enough to drive the device, and it is necessary to adjust the CPU core voltage. This is where PMM (**Power Management Module**) comes in. ```c void SetVcoreUp (unsigned int level) { // Open PMM registers for write PMMCTL0_H = PMMPW_H; // Set SVS/SVM high side new level SVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level; // Set SVM low side to new level SVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level; // Wait till SVM is settled while ((PMMIFG & SVSMLDLYIFG) == 0); // Clear already set flags PMMIFG &= ~(SVMLVLRIFG + SVMLIFG); // Set VCore to new level PMMCTL0_L = PMMCOREV0 * level; // Wait till new level reached if ((PMMIFG & SVMLIFG)) while ((PMMIFG & SVMLVLRIFG) == 0); // Set SVS/SVM low side to new level SVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level; // Lock PMM registers for write access PMMCTL0_H = 0x00; } void setup(void) { // Increase Vcore setting to level3 to support fsystem=25MHz // NOTE: Change core voltage one level at a time.. SetVcoreUp (0x01); SetVcoreUp (0x02); SetVcoreUp (0x03); } ``` For specific parameters, please refer to the manual. One thing to note is that the voltage level needs to be changed step by step and cannot be skipped. ## DMA The last point about MSP430F5529LP is that if you need to send control signals to the LED screen in a loop, you can consider using DMA to free up the CPU, reduce power consumption, and be flexible. A detailed example will be given later. MSP430F5529 has three DMA controllers: DMA0, DMA1, and DMA2. Each controller contains 32 trigger channels. In the figure below, DMAxSA is the source address and DMAxDA is the destination address. 
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 The corresponding relationship of DMA trigger channels can be found in the datasheet, and a screenshot is taken here. 
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 The subsequent example will use channel 19, that is, UCB0TXIFG, corresponding to the SPI send interrupt. That is, it triggers once every byte sent. See the example below for details. ## Code & Test Below we implement the driver code for WS2812B. The basic initialization part has been completed above. However, if you want to realize functions such as scanning the screen and lighting up the specified area, you need to expand it further. ### Dot matrix coordinate encoding As mentioned earlier, the LEDs on the dot matrix screen are arranged in an S-shaped pattern, but for the square matrix, we prefer to control each light by row and column, rather than by the snake-like movement of the colored lights. So it involves a **coordinate encoding**. In short, it is to find the specific number of the LED in the ribbon (0~63) according to the given row and column numbers. Here I draw a picture to illustrate this transformation rule. 
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 It is actually very simple. It is to calculate the id according to the difference between odd and even. ```c index=(row%2==0)?(row*8+col):(row*8+(7-col)) ``` In this way, the row and column coordinates (0, 0)-(7,7) are mapped to (0,63). Because it is simple after all, it can be defined with macros. ```c /* map coordinate to index of led matrix * coordinate: (0, 0) - (7, 7) * index: (0) - (63) */ #define INDEX(row, col) ((row)%2==0?((row)*8+(col)):((row)*8+(7-(col)))) ``` ### Scan the screen Scanning the screen is to traverse the LEDs. Each LED can use the same color or different colors. Using delay during the scanning process can produce animation effects. ```c // Fill the matrix with a solid color. This will update the matrix. void fillMatrix(uint8_t r, uint8_t g, uint8_t b) { int i; for (i = 0; i < NUM_LEDS; i++) { setLEDColor(i, r, g,b);  // set all LEDs to specified color
    }
    showMatrix();  // refresh matrix
}
void fillMatrixByRGB(uint32_t RGB) {
    int i;
    for (i = 0; i < NUM_LEDS; i++) {
        setLEDColorByRGB(i, RGB);  // set all LEDs to specified color
    }
    showMatrix();  // refresh matrix
}

// Clear the color of all LEDs (make them black/off)
void clearMatrix() {
    fillMatrix(0x00, 0x00, 0x00);  // black
}

// fill specific number of led matrix
void gradualFill(uint16_t n, uint8_t r, uint8_t g, uint8_t b){
    int i;
    for (i = 0; i < n; i++){        // n is number of LEDs
        setLEDColor(i, r, g, b);
        showMatrix();
        _delay_cycles(500000);       // lazy delay
    }
}
void gradualFillByRGB(uint16_t n, uint32_t RGB){
    int i;
    for (i = 0; i < n; i++){        // n is number of LEDs
        setLEDColorByRGB(i, RGB);
        showMatrix();
        _delay_cycles(500000);       // lazy delay
    }
}
```

`fillMatrix`, `fillMatrixByRGB`都是显示相同颜色，只不过参数不一样，类似函数重载。`clearMatrix`用于清空，也就是熄灭所有的灯。`gradualFill`, `gradualFillByRGB`可以产生动画，形成彩带循环更新的样式。

使用以下代码就可以在灰色背景下更新不同的颜色，然后熄灭。

```c
// Colors
#define COLOR_RED       (0xFF0000)
#define COLOR_GREEN     (0x00FF00)
#define COLOR_BLUE      (0x0000FF)
#define COLOR_WHITE     (0xFFFFFF)
#define COLOR_BLACK     (0x000000)
#define COLOR_CLEAR     (0x000000)
#define COLOR_YELLOW    (0xFFFF00)
#define COLOR_CYAN      (0x00FFFF)
#define COLOR_MAGENTA   (0xFF00FF)

fillMatrixByRGB(0x333333);
gradualFillByRGB(8, COLOR_RED);
gradualFillByRGB(16, COLOR_GREEN);
gradualFillByRGB(24, COLOR_BLUE);
gradualFillByRGB(32, COLOR_YELLOW);
gradualFillByRGB(40, COLOR_CYAN);
gradualFillByRGB(48, COLOR_MAGENTA);
gradualFillByRGB(56, COLOR_WHITE);
gradualFillByRGB(64, COLOR_CLEAR);
```

展示如下：

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### 矩阵显示

接下来看看坐标编码的应用，指定矩形区域点亮LED. 这里就用到了上面定义的坐标变换宏`INDEX`

```c
void setRectLEDColorByRGB(uint8_t row, uint8_t col, uint8_t width, uint8_t height, uint32_t RGB) {
    if (width < 1 || height < 1)
        return;

uint8_t row_end = row + width;
    uint8_t col_end = col + height;
    if (row_end > MATRIX_WIDTH)
        row_end = MATRIX_WIDTH;
    if (col_end > MATRIX_HEIGHT)
        col_end = MATRIX_HEIGHT;

uint8_t i, j;
    uint8_t id;
    for (i = row; i < row_end; i++)
        for (j = col; j < col_end; j++) {
            id = INDEX(i, j);
            setLEDColorByRGB(id, RGB);
        }
}
```

展示如下：

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### UART控制

对了，控制LED怎么少的了串口，蓝牙也是ok的，通过串口发送数据，然后显示不同的颜色和区域也是很有趣的。下面的代码是在启用uart和以上描述的代码基础上编写的。setup函数用于初始化硬件，main函数在初始化后进行一轮扫屏，然后等待串口输入，根据串口信息点亮指定区域。

```c
void init_uart()
{
    // USCI_A1 UART
    P4SEL |= BIT4+BIT5;                       // P4.4,5 = USCI_A1 TXD/RXD
    UCA1CTL1 |= UCSWRST;                      // **Put state machine in reset**
    UCA1CTL1 |= UCSSEL_2;                     // SMCLK
    UCA1BR0 = 145;                            // 16MHz 115200 (see User's Guide)
    UCA1BR1 = 0;                              // 16MHz 115200
    UCA1MCTL |= UCBRS_1 + UCBRF_0;            // Modulation UCBRSx=1, UCBRFx=0
    UCA1CTL1 &= ~UCSWRST;                     // **Initialize USCI state machine**
    UCA1IE |= UCRXIE;                         // Enable USCI_A1 RX interrupt
}

void setup()
{
    WDTCTL = WDTPW | WDTHOLD;   // stop watchdog timer
    P1DIR |= BIT0;

// Increase Vcore setting to level3 to support fsystem=25MHz
    // NOTE: Change core voltage one level at a time..
    SetVcoreUp (0x01);
    SetVcoreUp (0x02);
    SetVcoreUp (0x03);

init_ucs();
    init_uart();
    init_spi();
    clearMatrix();
    // fillMatrix(0xFF, 0x00, 0xFF);
}

volatile uint8_t chr = 0xFF;               // set a invalid value
int main(void)
{
    setup();
    __bis_SR_register(GIE);                   // interrupts enabled

// show time
    fillMatrixByRGB(0x333333);
    gradualFillByRGB(8, COLOR_RED);
    gradualFillByRGB(16, COLOR_GREEN);
    gradualFillByRGB(24, COLOR_BLUE);
    gradualFillByRGB(32, COLOR_YELLOW);
    gradualFillByRGB(40, COLOR_CYAN);
    gradualFillByRGB(48, COLOR_MAGENTA);
    gradualFillByRGB(56, COLOR_WHITE);
    gradualFillByRGB(64, COLOR_CLEAR);

uint8_t r=0x60, g=0x40, b=0x20;
	uint32_t RGB = 0xFFFFFF;
	while(1){
	    r+=33;
	    g+=66;
	    b+=77;
        if (r >= 0xFF)
            r = g + 0x03;
        if (g >= 0xFF)
            g = b + 0x05;
        if (b >= 0xFF)
            b = 0x06;

if (chr < 0xFF) {
            clearCache();
            RGB = (uint32_t)((r << 16) + (g << 8) + b);
            setRectLEDColorByRGB(r % 8, g % 8, 3, 3, RGB);
            setLEDColor(chr % NUM_LEDS, g, b, r);
            showMatrix();  // refresh strip
            chr = 0xFF;
//            gradualFill(8, r, g, b);
        }
        __delay_cycles(5000000);
	    P1OUT ^= 1;
	}
}

// Echo back RXed character, confirm TX buffer is ready first
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCI_A1_VECTOR
__interrupt void USCI_A1_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCI_A1_VECTOR))) USCI_A1_ISR (void)
#else
#error Compiler not supported!
#endif
{
    switch(__even_in_range(UCA1IV,4))
    {
        case 0:break;                             // Vector 0 - no interrupt
        case 2:                                   // Vector 2 - RXIFG
            while (!(UCA1IFG&UCTXIFG));           // USCI_A1 TX buffer ready?
            chr = UCA1RXBUF;
            UCA1TXBUF = chr;                      // TX -> RXed character
            break;
        case 4:break;                             // Vector 4 - TXIFG
        default:break; } } ``` 
<ignore_js_op>

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 ### DMA timed update LED OK, finally let's see how to light up using DMA. The specific principle has been explained. Here is the **complete code**. ```c #include<msp430.h>
#include <stdint.h>
#include<stdbool.h>

#define NUM_LEDS                64                                  // 64 LEDs matrix, configure this here
#define WS_BIT_0                0xc0                                // Bit 0
#define WS_BIT_1                0xf0                                // Bit 1
#define SIZE_OF_LED_ARRAY       (NUM_LEDS * 3 * 8)                  // DMA buffer, 24 bytes per LED

uint8_t led_raw[SIZE_OF_LED_ARRAY]; // DMA space, incl. 50usec break time

typedef struct {
    uint8_t r;
    uint8_t g;
    uint8_t b;
} led_color_t;      // led color struct

void init_ucs(void) {
    UCSCTL3 |= SELREF_2;                      // Set DCO FLL reference = REFO

__bis_SR_register(SCG0);                  // Disable the FLL control loop
    UCSCTL0 = 0x0000;                         // Set lowest possible DCOx, MODx
    UCSCTL1 = DCORSEL_5;                      // Select DCO range 24MHz operation
    UCSCTL2 = FLLD_1 + 499;                   // Set DCO Multiplier for 12MHz
                                              // (N + 1) * FLLRef = Fdco
                                              // (499 + 1) * 32768 = 16MHz
                                              // Set FLL Div = fDCOCLK/2
    __bic_SR_register(SCG0);                  // Enable the FLL control loop

// Worst-case settling time for the DCO when the DCO range bits have been
    // changed is n x 32 x 32 x f_MCLK / f_FLL_reference. See UCS chapter in 5xx
    // UG for optimization.
    // 32 x 32 x 16 MHz / 32,768 Hz = 500000 = MCLK cycles for DCO to settle
    __delay_cycles(500000);
}

/* timer_a0_init
 *
 * initalizes timerA0 to 10msec intervals, CCRO, running from REFO (32kHz)
 *
 */
void timer_a0_init(void) {
    TA0CCTL0 = CCIE;
    TA0CCR0 = 160;
    // ACLK, continous up, clear TAR
    TA0CTL = TASSEL_1 + MC__CONTINOUS + TACLR;
}

/*
 * init_spi
 * configures USCIA0 to SPI master ,8MHz clock rate, 8Bit, running from SMCLK
 *
 */
void init_spi(void) {
    P3SEL |= BIT0;                               // P3.0 SPI MOSI option select
    P1OUT &= ~BIT0;

UCB0CTL1 |= UCSWRST;                         // **Put state machine in reset**
    UCB0CTL0 |= UCMST + UCCKPH + UCMSB + UCSYNC; // 3-pin, 8-bit SPI master, MSB
    UCB0CTL1 |= UCSSEL_2; // SMCLK source (16 MHz)

UCB0BR0 = 0x03;       // 16 MHz / 3 = .1875 us per bit
    UCB0BR1 = 0;          //
    UCB0CTL1 &= ~UCSWRST; // Initialize USCI state machine
}

void init_dma(void) {
    // channel 19 = UCBTXIFG as trigger for DMA
    DMACTL0 = 0;
    DMACTL1 = DMA2TSEL_19;
    DMACTL2 = 0;
    DMACTL3 = 0;
    // DMA2 configuration
    // bytewise access for source and destination, increment source, single transfer
    DMA2CTL = DMADT_0 | DMASRCINCR_3 | DMASRCBYTE | DMADSTBYTE | DMAIE;
    DMA2SA = (uint16_t)(&led_raw[1]); // source
    DMA2DA = (uint16_t)&UCB0TXBUF;    // destination
    DMA2SZ = SIZE_OF_LED_ARRAY-1;     // size in bytes
}

/* SetVCoreUp
 * TI PMM driverlib Code to set Vcore to a given level
 *
 * this is complicated code, but apparently is needed to come around
 * erratum FLASH37
 * removed some original comments to compress code
 *
 */
uint16_t SetVCoreUp(uint8_t level)
{
    // Open PMM registers for write
    PMMCTL0_H = PMMPW_H;
    // Set SVS/SVM high side new level
    SVSMHCTL = SVSHE + SVSHRVL0 * level + SVMHE + SVSMHRRL0 * level;
    // Set SVM low side to new level
    SVSMLCTL = SVSLE + SVMLE + SVSMLRRL0 * level;
    // Wait till SVM is settled
    while ((PMMIFG & SVSMLDLYIFG) == 0);
    // Clear already set flags
    PMMIFG &= ~(SVMLVLRIFG + SVMLIFG);
    // Set VCore to new level
    PMMCTL0_L = PMMCOREV0 * level;
    // Wait till new level reached
    if ((PMMIFG & SVMLIFG))
    while ((PMMIFG & SVMLVLRIFG) == 0);
    // Set SVS/SVM low side to new level
    SVSMLCTL = SVSLE + SVSLRVL0 * level + SVMLE + SVSMLRRL0 * level;
    // Lock PMM registers for write access
    PMMCTL0_H = 0x00;
}

/* _set_single_color
 *
 * writes one brightness byte at the given location in the led array
 *
 * as the DMA uses the led array directly to output the bits over SPI
 * it must be deflated in advance in memory. One bit of WS2812 information
 * is one byte to transfer over SPI
 * -> bit1 = WS_BIT_1 and bit0 = WS_BIT_0
 *
 * disadvantage is that it uses 8x more RAM...
 *
 * this function is normally called by ::set_LED
 *
 * @param led_color_ptr     [in] pointer to location within the ::led_raw array
 * @param led_color         [in] single byte, represents the brightness
 */

void _set_single_color(uint8_t* led_color_ptr, uint8_t brightness)   {
    uint8_t i;
    uint8_t mask = 0x80;
    for (i=0; i<8; i++) {
        if (brightness & mask) {
            *led_color_ptr = WS_BIT_1;
        } else {
            *led_color_ptr = WS_BIT_0;
        }
        mask = mask >> 1;
        led_color_ptr++;
    }
}

/* set_LED
 *
 * writes the color information (RGB) of the given LED number
 * within the ::led_raw array
 *
 * @param led_nr            [in] position of LED within the matrix
 * @param led_color         [in] RGB information
 */
void set_LED(uint8_t led_nr, led_color_t* led_color) {
    uint8_t* led_ptr = led_raw + led_nr * 24;
    _set_single_color(led_ptr, led_color->g);
    _set_single_color(led_ptr+8, led_color->r);
    _set_single_color(led_ptr+16, led_color->b);
}

int main(void)
{
    uint16_t time = 0;
    led_color_t col;

WDTCTL = WDTPW + WDTHOLD;

// set vcore to highest value
    SetVCoreUp(0x01);
    SetVCoreUp(0x02);
    SetVCoreUp(0x03);

// hw init
    init_ucs();
    init_spi();
    timer_a0_init();
    init_dma();

// internal LED and debug pins
    P1DIR |= BIT0;
    __bis_SR_register(GIE);    // enable interrupts

// all set, now let the DMA run
    DMA2CTL |= DMAEN ;
    UCB0TXBUF = led_raw[0];
    while (1)
    {
        time++;
        P1OUT ^= BIT0;
        LPM0;
        // DMA transfer has finished, you may calculate LED updates now
        // timer A is triggered app. every 10msec, so you have around 6msec time
        // to update the matrix

// this is a color fading thing
        uint8_t i;
        for (i=0; i<num_leds; ##="" #elif="" #else="" #endif="" #error="" #if="" #pragma="" %="" ((interrupt(dma_vector)))="" ((interrupt(timer0_a0_vector)))="" (num_leds="" (taiv)="" (void)="" +="" -="" 0:="" 1="" 1024)="" 1024)+i;="" 10:="" 12:="" 14:="" 16:="" 256)="" 256);="" 2:="" 3="" 4="" 4:="" 5="" 512)="" 6="" 6:="" 7="" 8:="" ;="" [attach]513833[="" __attribute__="" __interrupt="" ```="" a="" application="" attach]="" back="" break;="" buffer="" can="" case="" channel="" channel2="" character,="" col.b="(time" col.g="(time" col.r="(time" compiler="" confirm="" default:="" defined(__gnuc__)="" defined(__iar_systems_icc__)="" defined(__ti_compiler_version__)="" div="" dma="" dma1ifg="DMA" dma2ctl="" dma2sa="(uint16_t)(&led_raw[1]);" dma3ifg="DMA" dma4ifg="DMA" dma5ifg="DMA" dma6ifg="DMA" dma7ifg="DMA" dma_isr="" dma_isr(void)="" dmaie="" do="" echo="" exit="" exits="" finished,="" first="" foreground="" from="" github.com="" handler,="" https:="" i);="" i*4;="" i++){="" i;="" interrupt="" is="" its="" just="" leds="" low="" lpm0_exit;="" mjmeli="" mode="" msp430-neopixel-ws2812-library<="" niwhsa9="" not="" of="" pmm等模块，还学会了ws2812b的spi控制方法。彩屏虽小，但是颜色可以随意变换，还可以设计很多好玩的动画，哈哈。篇幅和时间限制就先到这啦。欢迎交流讨论。="" power="" re-enables="" ready="" rxed="" set_led(i,&col);="" so="" source="" supported!="" switch(dmaiv)="" ta0ccr0="" that="" the="" timer0_a0_isr="" timer0_a0_isr(void)="" timera0="" to="" transfer="" tx="" ucb0txbuf="led_raw[0];" vector="" void="" work="" ws2182b_driver_for_msp430f5529="" {="" |="DMAEN" ||="" }="" 参考资料="" 小结="" 展示如下：="" 这次的实验学习和使用到的功能还不少，包含ucs，dma，spi，uart,="">
<div class="trtext" f="message_3030174"><p><img  height="50"  src="https://bbs.eeworld.com.cn/static/editor/plugins/hkemoji/sticker/facebook/wanwan33.gif"  width="58" onclick="zoom(this, this.getAttribute('zoomfile'), 0, 0, '0')" zoomfile="" file="" inpost="1" onmouseover="showMenu({'ctrlid':this.id,'pos':'12'})" lazyloaded="true" initialized="true">Really good information, both hardware and software are explained thoroughly, must be praised. Thanks for sharing.</p>
</div>
<div class="trtext" f="message_3030397"><p>Very detailed. Eagle PCB?</p>
</div>
<div class="trtext" f="subject_1149938">[MSP430F5529 Review] 6. DMA & SPI driving WS2812B color dot matrix screen</div>
<input id="trid" type="hidden" value="0"/>
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alan000345 · Published on 2020-12-10 21:44

Really good information, both hardware and software are explained thoroughly, must be praised. Thanks for sharing.

freebsder · Published on 2020-12-11 19:05

Very detailed. Eagle PCB?

[MSP430F5529 Review] 6. DMA & SPI driving WS2812B color dot matrix screen [Copy link]

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