{"id":158,"date":"2013-03-10T21:28:35","date_gmt":"2013-03-11T05:28:35","guid":{"rendered":"http:\/\/schminktronics.com\/blog\/?p=158"},"modified":"2013-03-27T14:38:38","modified_gmt":"2013-03-27T22:38:38","slug":"counter-test-1","status":"publish","type":"post","link":"http:\/\/schminktronics.com\/blog\/archives\/158","title":{"rendered":"Counter Test 1"},"content":{"rendered":"

My first test actually went quite well. The counter worked just like I expected and I got the counter information I wanted:<\/p>\n

\"LEDs<\/a>

LEDs displaying a binary pattern showing the value of the counter for how long the last rotation took. MSB is the innermost LED.<\/p><\/div>\n

For this picture, I used a flash, then kept the shutter open a bit. The spinner is actually traveling clockwise, so the trail of LEDs is actually in front of the spinner, not behind it as you would expect.<\/p>\n

Anyway–the reason I used the flash was so I could see where each of the LEDs was mounted and could accurately count which ones are off. The MSB is the innermost one, so this counter value is 100011000100000b\u00a0which is 4620h. This is about 2.5 times smaller than what I predicted. The counter values also change a lot more than I expected. I thought the least significant 2-3 bits would vary, but I actually see the least significant 8-9 bits changing. I know the battery is running low for my battery, so maybe<\/i>\u00a0the counter values I’m seeing are accurate.<\/p>\n

Here’s the code I used to do this:<\/p>\n\n

1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n11\n12\n13\n14\n15\n16\n17\n18\n19\n20\n21\n22\n23\n24\n25\n26\n27\n28\n29\n30\n31\n32\n33\n34\n35\n36\n37\n38\n39\n40\n41\n42\n43\n44\n45\n46\n47\n48\n49\n50\n51\n52\n53\n54\n55\n56\n57\n58\n59\n60\n61\n62\n<\/pre><\/td>
\/\/  Using the spinner board to test 328 counters<\/span>\n \n#include <SPI.h><\/span>\n \nconst<\/span> int<\/span> HALL  =<\/span>  2<\/span>;<\/span> \/\/ PD2<\/span>\nconst<\/span> int<\/span> BLANK =<\/span>  8<\/span>;<\/span> \/\/ PB0<\/span>\nconst<\/span> int<\/span> LAT   =<\/span>  9<\/span>;<\/span> \/\/ PB1<\/span>\n \nconst<\/span> int<\/span> HALL_INT =<\/span> 0<\/span>;<\/span> \/\/ Hall effect interrupt 0 on PD2 (INT0)<\/span>\n \nunsigned<\/span> int<\/span> savedCounter =<\/span> 0<\/span>;<\/span>\n \nvoid<\/span> hallStart(<\/span>void<\/span>)<\/span> {<\/span>\n  savedCounter =<\/span> TCNT1;<\/span>\n  TCNT1 =<\/span> 0<\/span>;<\/span>\n}<\/span>\n \nvoid<\/span> setup(<\/span>)<\/span> {<\/span>\n  digitalWrite(<\/span>LAT,<\/span> LOW)<\/span>;<\/span>\n  pinMode(<\/span>LAT,<\/span> OUTPUT)<\/span>;<\/span>     \n \n  digitalWrite(<\/span>BLANK,<\/span> HIGH)<\/span>;<\/span>\n  pinMode(<\/span>BLANK,<\/span> OUTPUT)<\/span>;<\/span>     \n \n  pinMode(<\/span>HALL,<\/span> INPUT_PULLUP)<\/span>;<\/span>\n \n  \/\/ Setup the 16 bit counter<\/span>\n  TCCR1A =<\/span> 0<\/span>;<\/span>                   \/\/ Turn off output compare modes<\/span>\n  TCCR1B =<\/span> 2<\/span>;<\/span>                   \/\/ Turn on clk\/8 input<\/span>\n \n  attachInterrupt(<\/span>HALL_INT,<\/span> hallStart,<\/span> FALLING)<\/span>;<\/span>\n \n  SPI.begin<\/span>(<\/span>)<\/span>;<\/span>\n  SPI.setDataMode<\/span>(<\/span>SPI_MODE0)<\/span>;<\/span>\n  SPI.setBitOrder<\/span>(<\/span>LSBFIRST)<\/span>;<\/span>\n  SPI.setClockDivider<\/span>(<\/span>SPI_CLOCK_DIV2)<\/span>;<\/span> \/\/ Datasheet says 35 MHz max, so 8 MHz is fine<\/span>\n \n  TCNT1 =<\/span> 0<\/span>;<\/span>\n}<\/span>\n \nvoid<\/span> setLeds(<\/span>unsigned<\/span> int<\/span> pattern)<\/span> {<\/span>\n  \/\/ Blank the LEDS<\/span>\n  digitalWrite(<\/span>BLANK,<\/span> HIGH)<\/span>;<\/span>\n \n  \/\/ Transfer the data<\/span>\n  SPI.transfer<\/span>(<\/span>pattern &<\/span> 0xFF<\/span>)<\/span>;<\/span>\n  SPI.transfer<\/span>(<\/span>pattern >><\/span> 8<\/span>)<\/span>;<\/span>\n \n  \/\/ Latch the data<\/span>\n  digitalWrite(<\/span>LAT,<\/span> HIGH)<\/span>;<\/span>\n  digitalWrite(<\/span>LAT,<\/span> LOW)<\/span>;<\/span>\n \n  \/\/ Unblank the LEDS<\/span>\n  digitalWrite(<\/span>BLANK,<\/span> LOW)<\/span>;<\/span>\n}<\/span>\n \nvoid<\/span> loop(<\/span>)<\/span> {<\/span>\n  if<\/span> (<\/span>savedCounter !=<\/span> 0<\/span>)<\/span> {<\/span>\n    setLeds(<\/span>savedCounter)<\/span>;<\/span>\n    savedCounter =<\/span> 0<\/span>;<\/span>\n  }<\/span>\n}<\/span><\/pre><\/td><\/tr><\/table><\/div>\n\n
So, the only way to find out if my counter values are correct is to do the next test:<\/p>\n