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Found 3 results

  1. I am trying to create a manual demonstration circuit for a 74HC595 (here is the datesheet of 74HC595)shift register. Se my circuit below. The problem I am having is that I am only getting a +0.7V signal to the data, clock, and latch pins of the 74HC595 when one of the buttons are pushed. The S4 RESET switch works fine (normally high at 5V, press switch to bring down to 0V), however S1, S2, and S3 do not accomplish the reverse scenario (normally LOW, press switch for HIGH) correctly. You will note that I am also trying to debounce the switching with a capacity or resistor. I suspect this debouncing set up is creating my problem. Does anybody have any advice on how to create a debounced normally LOW, momentarily HIGH switch that switches between 0V and 5V?
  2. DanielPHuber

    4 Digit display from Qifei

    A display is a nice thing to have in many projects. A very cheap solution for only 2$ to 4$ is a 4 digit display from Qifei that can be found e.g. at www.Aliexpress.com. Of course, for this price you do not get a user manual! But what beats me is that I could not find a usable description on the internet. Therefore I had to rely on trial and error. Here is what I learned. The device has 2 cascaded 74HC595 shift registers, one for the digit select, the other for segements select. By this the deviceu can only display one digit at a time. Therefore, you must time multiplex the for digits fast enough that there is no flickering visible. Communication is serial, either by Bit banging or you may comfortably use the bult in SPI with the MSP430G2553 CPU. Energia is a very valuable tool for jobs like this. SPI will shift the data into the shift registers, but to output the data you have to shake (rising edge) the RCLK line, this will latch the output lines. Unfortunately this is not implemented in the Energia library for MSP430 (although the manual claims it) and you have to do it "by hand". Negative logic is used to display a digit. That is, a 1 bit switches the corresponding segment off. The segments of a single digit are numbered like: 0 5 1 6 4 2 3 7 where 7 is the decimal point. E.g. to display a 0 with a decimal point you would send: B01000000 The device has 5 input pins: Vcc: 3-5V Gnd DIO: the data signal SCLK: the clock signal, data will be read on the rising edge RCLK: on the rising edge of this signal the data and address will be latched to the output lines of the shift register Details of the interface can be seen in the following example program. It is a counter that counts 1/10 seconds. The interface is in the subroutine "set": // example for interfacing the 4 digit display from Qifei // 1/10 sec counter // The display can only show one single digit at a time. We // therefore need to time multiplex the display fast enough. #include <SPI.h> #define RCLK P2_0 // latch #define SCLK P1_5 // clock #define MOSI P1_7 // data to display //#define MISO P1_6 // data from peripherie, not used here const byte digit[] = //seven segment (+ 1 decimal point) bits { B11000000, //0 B11111001, //1 B10100100, //2 B10110000, //3 B10011001, //4 B10010010, //5 B10000010, //6 B11111000, //7 B10000000, //8 B10010000, //9 B10001000, //A B10000011, //b B11000110, //C B10100001, //d B10000110, //E B10001110 //F }; byte colDig[4] = // digits { B00000001, // digit 1 B00000010, // digit 2 B00000100, // digit 3 B00001000, // digit 4 }; byte dp= B01111111; //Decimal point. AND (&) with data byte empty= B11111111; // clear void setup() { pinMode (RCLK, OUTPUT); digitalWrite(RCLK,LOW); SPI.begin(); // SPI.setDataMode(SPI_MODE0); //default // SPI.setBitOrder(MSBFIRST); //default } void loop() { int del=1; long val=millis(); //decimal while(val>=1000000L) val-= 1000000L; int t1= val/100000L; val-= t1*100000L; int t2= val/10000L; val-= t2*10000L; int t3= val/1000L; val-= t3*1000L; int t4= val/100L; val-= t4*100L; // hexadecimal /* val/=100; int t1= val/4096L; val-= t1*4096L; int t2= val/256L; val-= t2*256L; int t3= val/16L; val-= t3*16L; int t4= val; */ for(int i1=0;i1<4;i1++){ set(digit[t1],colDig[3]);delay(del); set(digit[t2],colDig[2]);delay(del); set(digit[t3] & dp,colDig[1]);delay(del); set(digit[t4],colDig[0]);delay(del); set(empty,colDig[0]); } } // set one digit void set(byte val, byte dig){ digitalWrite(RCLK,LOW); SPI.transfer(val); // value SPI.transfer(dig); // which digit digitalWrite(RCLK,HIGH); } Note that there is a similar device with the TM1637 chip that is different from what I described here.
  3. Hello everyone! I'm continuing my project of creating an RGB LED matrix capable of displaying live images being transmitted from a laptop via a serial cable to the MSP430G2553. At the moment, I'm coding four 8x8 Common Anode RGB LED matrices joined together to create a 16x16 display. Hardware I'm using: - 3 * TLC5940s (one for each colour) - 2 * 74HC595 shift registers (drives the columns/anodes) I'm using code provided by RobG from this link <http://forum.43oh.com/topic/2315-tlc5940-examples/> and this one <http://forum.43oh.com/topic/3328-rgb-to-hsv-conversion-with-msp430g2231-help/#entry29106> in order to drive the LEDs with PWM enabled. BUT, the problem I'm having is that I'm trying to allow every pixel to have different colours, but when running, the microcontroller isn't refreshing the pixels fast enough so there is MASSIVE flickering - which isn't ideal.... Here is the code from which I am working : feel free to insult :-P #include <msp430g2553.h> #include <msp430.h> // Need to sort hsv2rgb because yellow is pish... // u_long is 32 bits so 2^32 - 1 is max value. Need more for 32x32 matrix // TLC inputs #define VPRG_PIN BIT0 // TIE TO GND? #define GSCLK_PIN BIT4 #define SCLK_PIN BIT5 #define DATA BIT6 // DS -> 1.6 | 595 DATA PIN #define MOSI_PIN BIT7 #define MOSI595 BIT2 // 595 data pin ? THIS ISNT DOING ANYTHING #define DCPRG_PIN BIT0 // TIE IT TO GND? #define XLAT_PIN BIT1 #define BLANK_PIN BIT2 #define CLOCK BIT3 // SH 11 -> 2.3 // 595 OUTPUTS #define LATCH BIT4 // ST 12 -> 2.4t typedef unsigned char u_char; typedef unsigned int u_int; typedef unsigned short u_short; typedef unsigned long u_long; // ================================// // Prototypes // // ================================// void init( void ); void SPI_setup( void ); void updateTLC( void ); void shiftOut( u_long ); void HSV2RGB( u_short*, u_short*, u_short*, short, u_char); void set_row_char_hue (u_char, u_long, short, u_char); void row_refresh(u_char,short,short,short,short,short,short,short,short,short,short,short,short,short,short,short,short); #define NUMBER_OF_OUTS 48 // TLC OUTPUTS #define NUMBER_OF_ROWS 8 #define NUMBER_OF_COLUMNS 16 #define max_COLUMN NUMBER_OF_COLUMNS-1 #define max_ROW NUMBER_OF_ROWS-1 #define OFF 0 u_short leds[NUMBER_OF_OUTS]; // 0 - 15 Red Rows, 16 - 31 Blue Rows, 32 - 47 Green Rows {0, } u_char timerCounter = 0; void init(void) { WDTCTL = WDTPW + WDTHOLD; // disable WDT BCSCTL1 = CALBC1_16MHZ; // 16MHz clock DCOCTL = CALDCO_16MHZ; BCSCTL2 |= DIVS_0; // divide clock by 1 P1OUT &= ~(VPRG_PIN); P1DIR |= (VPRG_PIN + GSCLK_PIN + DATA); // port 1.4 configured as SMCLK out P1SEL |= GSCLK_PIN; P2DIR |= (BLANK_PIN + XLAT_PIN + CLOCK + LATCH + DCPRG_PIN); P2OUT &= ~(BLANK_PIN + XLAT_PIN); P2OUT &= ~DCPRG_PIN; // setup timer CCR0 = 0xFFF; TACTL = TASSEL_2 + MC_1 + ID_0; // SMCLK, up mode, 1:1 CCTL0 = CCIE; // CCR0 interrupt enabled } void SPI_setup(void) { // setup UCA0 ----UCA0 ISNT DOING ANYTHING YET! SHOULD I CONFIGURE THE 595's TO BE CONTROLLED BY SPI? P1SEL |= MOSI595; // p1.2 P1SEL2 |= MOSI595; // UCA0SIMO UCA0CTL0 = UCCKPH + UCMSB + UCMST + UCSYNC; // data captured on 1st UCLK edge/changed on follwing edge, MSB first, master, 3-pin SPI,synchronous UCA0CTL1 |= UCSSEL_2; // SMCLK UCA0BR0 |= 0x01; // 1:1 UCA0BR1 = 0; UCA0CTL1 &= ~UCSWRST; // clear SW // setup UCB0 P1SEL |= SCLK_PIN + MOSI_PIN; // pins 5 + 7 P1SEL2 |= SCLK_PIN + MOSI_PIN; // UCB0CLK + UCB0SIMO UCB0CTL0 = UCCKPH + UCMSB + UCMST + UCSYNC; // data captured on 1st UCLK edge/changed on follwing edge, MSB first, master, 3-pin SPI,synchronous UCB0CTL1 |= UCSSEL_2; // SMCLK UCB0BR0 |= 0x01; // 1:1 UCB0BR1 = 0; UCB0CTL1 &= ~UCSWRST; // clear SW } void main(void) { init(); SPI_setup(); updateTLC(); P2OUT |= (XLAT_PIN); P2OUT &= ~(XLAT_PIN); short o = 240; short y = 60; // yellow short b = 240; // blue short hue = 0; _bis_SR_register(GIE); for(; { // creates box image row_refresh(0, b,b,b,b,b,b,b,b,b,b,b,b,b,b,b,; row_refresh(1, b,y,y,y,y,y,y,y,y,y,y,y,y,y,y,; row_refresh(2, b,y,b,b,b,b,b,b,b,b,b,b,b,b,y,; row_refresh(3, b,y,b,y,y,y,y,y,y,y,y,y,y,b,y,; row_refresh(4, b,y,b,y,b,b,b,b,b,b,b,b,y,b,y,; row_refresh(5, b,y,b,y,b,y,y,y,y,y,y,b,y,b,y,; row_refresh(6, b,y,b,y,b,y,b,b,b,b,y,b,y,b,y,; row_refresh(7, b,y,b,y,b,y,b,y,y,b,y,b,y,b,y,; row_refresh(8, b,y,b,y,b,y,b,y,y,b,y,b,y,b,y,; row_refresh(9, b,y,b,y,b,y,b,b,b,b,y,b,y,b,y,; row_refresh(10, b,y,b,y,b,y,y,y,y,y,y,b,y,b,y,; row_refresh(11, b,y,b,y,b,b,b,b,b,b,b,b,y,b,y,; row_refresh(12, b,y,b,y,y,y,y,y,y,y,y,y,y,b,y,; row_refresh(13, b,y,b,b,b,b,b,b,b,b,b,b,b,b,y,; row_refresh(14, b,y,y,y,y,y,y,y,y,y,y,y,y,y,y,; row_refresh(15, b,b,b,b,b,b,b,b,b,b,b,b,b,b,b,; _bis_SR_register(LPM0_bits); // go to sleep } // end of for(; loop } void updateTLC(void) // RobG's code { u_char ledCounter = NUMBER_OF_OUTS >> 1; while (ledCounter-- > 0) { u_char i = ledCounter << 1; UCB0TXBUF = leds[i + 1] >> 4; while (!(IFG2 & UCB0TXIFG)); // TX buffer ready? u_char unib = leds[i + 1] << 4; u_char lnib = (leds[i] >> 8) & 0x0F; UCB0TXBUF = unib | lnib; while (!(IFG2 & UCB0TXIFG)) ; // TX buffer ready? UCB0TXBUF = leds[i]; while (!(IFG2 & UCB0TXIFG)); // TX buffer ready? } } void row_refresh(u_char row,short a,short b,short c,short d,short e,short f,short g,short h,short i,short j,short k,short l,short m,short n,short o,short p) { // this function checks if led is supposed to be ON // for example, if row = 0, and a = 360 then the top left led is OFF // if a = 120, then the led will be ON, and will be assigned the appropriate hue (green) u_long col_data = 0x0000; if(a < 360){col_data = 0x8000; set_row_char_hue(row,col_data,a,1);} // 0 if(b < 360){col_data = 0x4000; set_row_char_hue(row,col_data,b,1);} // 1 if(c < 360){col_data = 0x2000; set_row_char_hue(row,col_data,c,1);} // 2 if(d < 360){col_data = 0x1000; set_row_char_hue(row,col_data,d,1);} // 3 if(e < 360){col_data = 0x0800; set_row_char_hue(row,col_data,e,1);} // 4 if(f < 360){col_data = 0x0400; set_row_char_hue(row,col_data,f,1);} // 5 if(g < 360){col_data = 0x0200; set_row_char_hue(row,col_data,g,1);} // 6 if(h < 360){col_data = 0x0100; set_row_char_hue(row,col_data,h,1);} // 7 if(i < 360){col_data = 0x0080; set_row_char_hue(row,col_data,i,1);} // 8 if(j < 360){col_data = 0x0040; set_row_char_hue(row,col_data,j,1);} // 9 if(k < 360){col_data = 0x0020; set_row_char_hue(row,col_data,k,1);} // 10 if(l < 360){col_data = 0x0010; set_row_char_hue(row,col_data,l,1);} // 11 if(m < 360){col_data = 0x0008; set_row_char_hue(row,col_data,m,1);} // 12 if(n < 360){col_data = 0x0004; set_row_char_hue(row,col_data,n,1);} // 13 if(o < 360){col_data = 0x0002; set_row_char_hue(row,col_data,o,1);} // 14 if(p < 360){col_data = 0x0001; set_row_char_hue(row,col_data,p,1);} // 15 } void set_row_char_hue (u_char row, u_long col_data, short hue, u_char bool) { u_char led = 0; u_long byte; for(led = 0 ; led < 16 ; led++ ) { byte = (col_data>>led)&(0x01); if( byte ) { HSV2RGB( &leds[row], &leds[row + 32], &leds[row + 16], hue, bool); //on; shiftOut( col_data ); } } // turn off leds leds[row] = OFF; leds[row+32] = OFF; leds[row+16] = OFF; } void HSV2RGB(u_short* r, u_short* g, u_short* b, short h, u_char bool) { const u_char s = 255; u_char v = 255; u_char i, p, q, t; u_short fs; if (h < 60 ) i = 0; else if (h < 120) i = 1; else if (h < 180) i = 2; else if (h < 240) i = 3; else if (h < 300) i = 4; else if (h < 360) i = 5; else return; fs = ((h - i * 60) * s)/ 60; p = 255 - s; q = 255 - fs; t = 255 - s + fs; switch(i) { case 0: *r = 255;*g = t;*b = p;break; case 1: *r = q;*g = 255;*b = p;break; case 2: *r = p;*g = 255;*b = t;break; case 3: *r = p;*g = q;*b = 255;break; case 4: *r = t;*g = p;*b = 255;break; case 5: *r = 255;*g = p;*b = q;break; } if ( bool == 1 ) { *r *= v/16; *g *= v/16; *b *= v/16; } else { *r *= 0; *g *= 0; *b *= 0; } } #pragma vector = TIMER0_A0_VECTOR __interrupt void Timer_A0(void) { // 4096 GS clock cycles have been generated, time to restart PWM P2OUT |= (BLANK_PIN); P2OUT |= (XLAT_PIN); P2OUT &= ~(XLAT_PIN); P2OUT &= ~(BLANK_PIN); // increase timer counter timerCounter++; if (timerCounter == 1) // this is also from RobG, except updateTLC is every interrupt because otherwise it is far too slow { // is it time to for next frame? updateTLC(); // data was already prepared by main loop when it was awake last time timerCounter = 0; _bic_SR_register_on_exit(LPM0_bits); // wake up main loop so that it can prepare data for the next frame } } void shiftOut(u_long val) { P2OUT &= ~LATCH; int i; for (i = 0; i < 16; i++) // iterate over each bit 16 { if(val & (1 << i)) { P1OUT |= DATA; } else { P1OUT &= ~DATA; } P2OUT |= CLOCK; // PULSE CLOCK P2OUT ^= CLOCK; } // } P2OUT |= LATCH; // PULSE LATCH P2OUT &= ~LATCH; } If anyone has any suggestions on how to improve this code, it will be greatly appreciated, because I've really hit a wall with it. I did think that using SPI P1.2 for UCA0SIMO instead of the shiftOut() function might be a solution but I don't know how to go about doing that. Keep in mind that soon I'll be using P1.1 for RXD. Cheers!
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