Hi! Does anyone know how to make the chain from 3(or more) hc165 registers?
I did this example. The problem is:
When i made a chain from 2 registeres it worked fine!
#define NUMBER_OF_SHIFT_CHIPS [b]2[/b]
#define BYTES_VAL_T unsigned[b] int[/b]
But, when i add 3rd register
#define NUMBER_OF_SHIFT_CHIPS [b]3[/b]
#define BYTES_VAL_T unsigned[b] long[/b]
The 1st one stopped to work! It doesnt recognise button pressed.
Why?? Here is the code and scheme(Buttons are on every input!!! I didn't draw them all!)
/* How many shift register chips are daisy-chained.
*/
#define NUMBER_OF_SHIFT_CHIPS 3
/* Width of data (how many ext lines).
*/
#define DATA_WIDTH NUMBER_OF_SHIFT_CHIPS * 8
/* Width of pulse to trigger the shift register to read and latch.
*/
#define PULSE_WIDTH_USEC 5
/* Optional delay between shift register reads.
*/
#define POLL_DELAY_MSEC 20
/* You will need to change the "int" to "long" If the
* NUMBER_OF_SHIFT_CHIPS is higher than 2.
*/
#define BYTES_VAL_T unsigned long
int ploadPin = 8; // Connects to Parallel load pin the 165
int clockEnablePin = 9; // Connects to Clock Enable pin the 165
int dataPin = 11; // Connects to the Q7 pin the 165
int clockPin = 12; // Connects to the Clock pin the 165
BYTES_VAL_T pinValues;
BYTES_VAL_T oldPinValues;
/* This function is essentially a "shift-in" routine reading the
* serial Data from the shift register chips and representing
* the state of those pins in an unsigned integer (or long).
*/
BYTES_VAL_T read_shift_regs()
{
byte bitVal;
BYTES_VAL_T bytesVal = 0;
/* Trigger a parallel Load to latch the state of the data lines,
*/
digitalWrite(clockEnablePin, HIGH);
digitalWrite(ploadPin, LOW);
delayMicroseconds(PULSE_WIDTH_USEC);
digitalWrite(ploadPin, HIGH);
digitalWrite(clockEnablePin, LOW);
/* Loop to read each bit value from the serial out line
* of the SN74HC165N.
*/
for(int i = 0; i < DATA_WIDTH; i++)
{
bitVal = digitalRead(dataPin);
/* Set the corresponding bit in bytesVal.
*/
bytesVal |= (bitVal << ((DATA_WIDTH-1) - i));
/* Pulse the Clock (rising edge shifts the next bit).
*/
digitalWrite(clockPin, HIGH);
delayMicroseconds(PULSE_WIDTH_USEC);
digitalWrite(clockPin, LOW);
}
return(bytesVal);
}
/* Dump the list of zones along with their current status.
*/
void display_pin_values()
{
Serial.print("Pin States:\r\n");
for(int i = 0; i < DATA_WIDTH; i++)
{
Serial.print(" Pin-");
Serial.print(i);
Serial.print(": ");
if((pinValues >> i) & 1)
Serial.print("HIGH");
else
Serial.print("LOW");
Serial.print("\r\n");
}
Serial.print("\r\n");
}
void setup()
{
Serial.begin(9600);
/* Initialize our digital pins...
*/
pinMode(ploadPin, OUTPUT);
pinMode(clockEnablePin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, INPUT);
digitalWrite(clockPin, LOW);
digitalWrite(ploadPin, HIGH);
/* Read in and display the pin states at startup.
*/
pinValues = read_shift_regs();
display_pin_values();
oldPinValues = pinValues;
}
void loop()
{
/* Read the state of all zones.
*/
pinValues = read_shift_regs();
/* If there was a chage in state, display which ones changed.
*/
if(pinValues != oldPinValues)
{
Serial.print("*Pin value change detected*\r\n");
display_pin_values();
oldPinValues = pinValues;
}
delay(POLL_DELAY_MSEC);
}