{"id":19,"date":"2013-10-02T13:00:00","date_gmt":"2013-10-02T12:00:00","guid":{"rendered":""},"modified":"2023-08-18T12:12:44","modified_gmt":"2023-08-18T11:12:44","slug":"binary-clock-2","status":"publish","type":"post","link":"https:\/\/blog.hslracing.com\/electronics\/2013\/10\/binary-clock-2.html","title":{"rendered":"Binary Clock 2"},"content":{"rendered":"

Well I finally wired this all up on the breadboard and left it running for about half a day, but it has some serious time loss issues.<\/p>\n

\"\"<\/a><\/div>\n
As you can see it is running with the internal clock at 8Mhz as there is no external crystal.<\/div>\n
<\/div>\n
Writing this then made me realise why it is losing so much time – my previous test was with a 16MHz crystal and counting to 16000 for each second.<\/div>\n
<\/div>\n
I dropped the counter to 8000 and it was now about 2 seconds fast per minute, so I upped it to 8192 and it is now pretty close to exactly a minute, I let it run for a bit before adjusting further to 8200, this has run for about a day now and is still telling good time.<\/div>\n
<\/div>\n
There is a little flicker across the LEDs occasionally depending on how many are lit, and some of the Red Hour LEDs seem to have a very low level of light when other LEDs are lit.<\/div>\n
<\/div>\n
The latter condition is due to a forward voltage issue with\u00a0Charlieplexing<\/a>, whereby a small amount of voltage is hitting the Red LEDs and causing them to light due to shorter current paths, and Red LEDs lighting at around 1.3V compared to Blue at around 3V.<\/div>\n
<\/div>\n
I could get around this issue by either using LEDs of all the same colour, LEDs that all have the same forward voltage or adding some additional diodes to the Red connections, similar issues would also be seen with RGB LEDs in a charlieplex configuration.<\/div>\n
<\/div>\n
I may also try adding NPN transistors in an emitter follower configuration to make them brighter and reduce the load on the I\/O ports.<\/div>\n
<\/div>\n
I have also developed another version of this clock, but using the DS1307<\/a> real time clock chip mentioned in the previous post, just to see how easy\/difficult it was from both a hardware and software perspective.<\/div>\n
<\/div>\n
I built this one on the breadboard as well, here is the schematic:<\/div>\n
\"\"<\/div>\n
And here is the code – most of it is simply the “set time” example that comes with the DS1307 Arduino library<\/a>\u00a0joined up with my code for displaying the time on the Charlieplexed LEDs, and some debug serial output:<\/div>\n
<\/div>\n
#include <DS1307RTC.h><\/span><\/div>\n
#include <Time.h><\/span><\/div>\n
#include <Wire.h><\/span><\/div>\n
\u00a0<\/span><\/div>\n
#define DEBUG 1 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ set debug mode (2 = all debug, 1 = just time)<\/span><\/div>\n
\u00a0<\/span><\/div>\n
const int nPins = 3;<\/span><\/div>\n
const int pins[] = {6, 7, 8};<\/span><\/div>\n
const int clock[6][2] = { {7, 8}, {8, 7}, {6, 7}, {7, 6}, {6, 8}, {8, 6} };<\/span><\/div>\n
const char *monthName[12] = { “Jan”, “Feb”, “Mar”, “Apr”, “May”, “Jun”, “Jul”, “Aug”, “Sep”, “Oct”, “Nov”, “Dec”<\/span><\/div>\n
};<\/span><\/div>\n
\u00a0<\/span><\/div>\n
tmElements_t tm;<\/span><\/div>\n
int lastsec = 0;<\/span><\/div>\n
\u00a0<\/span><\/div>\n
void setup() {<\/span><\/div>\n
\u00a0 bool parse=false;<\/span><\/div>\n
\u00a0 bool config=false;<\/span><\/div>\n
\u00a0 \/\/ RTC should keep time with just battery and not actually need this section to run<\/span><\/div>\n
\u00a0 if (getDate(__DATE__) && getTime(__TIME__)) { \u00a0\/\/ get the date and time the compiler was run<\/span><\/div>\n
\u00a0 \u00a0 parse = true;<\/span><\/div>\n
\u00a0 \u00a0 \/\/if (makeTime(tm) < now()) {<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 if (RTC.write(tm)) { \u00a0 \u00a0 \/\/ and configure the RTC with this info<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 \u00a0 config = true;<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 }<\/span><\/div>\n
\u00a0 \u00a0 \/\/}<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
#ifdef DEBUG \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ debug output<\/span><\/div>\n
\u00a0 Serial.begin(9600); \u00a0 \u00a0 \u00a0 \u00a0\/\/ set serial port speed<\/span><\/div>\n
\u00a0 while (!Serial); \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \/\/ wait for serial connection<\/span><\/div>\n
\u00a0 delay(200);<\/span><\/div>\n
\u00a0 Serial.println(“LedPlex4 Debug Output”);<\/span><\/div>\n
\u00a0 Serial.println(“=====================”);<\/span><\/div>\n
\u00a0 if (parse && config) {<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(“DS1307 configured Time=”);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(__TIME__);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(“, Date=”);<\/span><\/div>\n
\u00a0 \u00a0 Serial.println(__DATE__);<\/span><\/div>\n
\u00a0 \u00a0 \/\/Serial.println(makeTime(tm));<\/span><\/div>\n
\u00a0 \u00a0 \/\/Serial.println(now());<\/span><\/div>\n
\u00a0 } else if (parse) {<\/span><\/div>\n
\u00a0 \u00a0 Serial.println(“DS1307 Communication Error :-{“);<\/span><\/div>\n
\u00a0 \u00a0 Serial.println(“Please check your circuitry”);<\/span><\/div>\n
\u00a0 } else {<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(“Could not parse info from the compiler, Time=””);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(__TIME__);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(“”, Date=””);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(__DATE__);<\/span><\/div>\n
\u00a0 \u00a0 Serial.println(“””);<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
#endif<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
bool getTime(const char *str)<\/span><\/div>\n
{<\/span><\/div>\n
\u00a0 int Hour, Min, Sec;<\/span><\/div>\n
\u00a0<\/span><\/div>\n
\u00a0 if (sscanf(str, “%d:%d:%d”, &Hour, &Min, &Sec) != 3) return false;<\/span><\/div>\n
\u00a0 tm.Hour = Hour;<\/span><\/div>\n
\u00a0 tm.Minute = Min;<\/span><\/div>\n
\u00a0 tm.Second = Sec;<\/span><\/div>\n
\u00a0 return true;<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
bool getDate(const char *str)<\/span><\/div>\n
{<\/span><\/div>\n
\u00a0 char Month[12];<\/span><\/div>\n
\u00a0 int Day, Year;<\/span><\/div>\n
\u00a0 uint8_t monthIndex;<\/span><\/div>\n
\u00a0<\/span><\/div>\n
\u00a0 if (sscanf(str, “%s %d %d”, Month, &Day, &Year) != 3) return false;<\/span><\/div>\n
\u00a0 for (monthIndex = 0; monthIndex < 12; monthIndex++) {<\/span><\/div>\n
\u00a0 \u00a0 if (strcmp(Month, monthName[monthIndex]) == 0) break;<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
\u00a0 if (monthIndex >= 12) return false;<\/span><\/div>\n
\u00a0 tm.Day = Day;<\/span><\/div>\n
\u00a0 tm.Month = monthIndex + 1;<\/span><\/div>\n
\u00a0 tm.Year = CalendarYrToTm(Year);<\/span><\/div>\n
\u00a0 return true;<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
void turnon(int led) {<\/span><\/div>\n
\u00a0 int Vcc = clock[led][0];<\/span><\/div>\n
\u00a0 int Gnd = clock[led][1];<\/span><\/div>\n
\u00a0 pinMode(Vcc, OUTPUT);<\/span><\/div>\n
\u00a0 pinMode(Gnd, OUTPUT);<\/span><\/div>\n
\u00a0 digitalWrite(Vcc, HIGH);<\/span><\/div>\n
\u00a0 digitalWrite(Gnd, LOW);<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
void alloff() {<\/span><\/div>\n
\u00a0 for (int i = 0; i < nPins; i++) {<\/span><\/div>\n
\u00a0 \u00a0 digitalWrite(pins[i], LOW);<\/span><\/div>\n
\u00a0 \u00a0 pinMode(pins[i], INPUT);<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
void showtime(int Value, int Width, int Offset) {<\/span><\/div>\n
\u00a0 int mask;<\/span><\/div>\n
\u00a0 \u00a0 for (int i = 0; i < Width; i++) {<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 mask = 1 << i; \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ shift bit mask by current position<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 if (HIGH && (Value & mask)) { \u00a0 \u00a0 \u00a0\/\/ check if LED should be lit<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 \u00a0 turnon(Offset + i); \u00a0 \/\/ turn on the LED<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 \u00a0 alloff();<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 }<\/span><\/div>\n
\u00a0<\/span><\/div>\n
#if DEBUG == 2 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ debug output<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(“Mask: “);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(mask, BIN);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(” On or Off: “);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(HIGH && (Value & mask), BIN);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(” LED: “);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.print(Offset + i, DEC);<\/span><\/div>\n
\u00a0 \u00a0 \u00a0 Serial.println(“”);<\/span><\/div>\n
#endif<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
}<\/span><\/div>\n
\u00a0<\/span><\/div>\n
void loop() {<\/span><\/div>\n
\u00a0 tmElements_t tm;<\/span><\/div>\n
\u00a0 if (RTC.read(tm)) {<\/span><\/div>\n
\u00a0 \u00a0 showtime(tm.Second, 6, 0); \u00a0 \/\/ Display seconds (LEDs 0-5)<\/span><\/div>\n
\u00a0 \/\/showtime(tm.Minute, 6, 6); \u00a0 \/\/ Display minutes (LEDs 6-11)<\/span><\/div>\n
\u00a0 \/\/showtime(tm.Hour, 5, 12); \u00a0 \u00a0\/\/ Display hours (LEDs 12-16)<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
\u00a0\u00a0<\/span><\/div>\n
#ifdef DEBUG \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\/\/ Debug output<\/span><\/div>\n
\u00a0 if (lastsec != tm.Second) {<\/span><\/div>\n
\u00a0 \u00a0 lastsec = tm.Second;<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(“Hours: “);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(tm.Hour, DEC);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(” Minutes: “);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(tm.Minute, DEC);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(” Seconds: “);<\/span><\/div>\n
\u00a0 \u00a0 Serial.print(tm.Second, DEC);<\/span><\/div>\n
\u00a0 \u00a0 Serial.println(“”);<\/span><\/div>\n
\u00a0 }<\/span><\/div>\n
#endif<\/span><\/div>\n
}<\/span><\/div>\n","protected":false},"excerpt":{"rendered":"

Well I finally wired this all up on the breadboard and left it running for about half a day, but it has some serious time loss issues. As you can see it is running with the internal clock at 8Mhz as there is no external crystal. Writing this then made me realise why it is…<\/p>\n","protected":false},"author":2,"featured_media":116,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[2],"class_list":["post-19","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorised","tag-binary-clock"],"_links":{"self":[{"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/posts\/19","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/comments?post=19"}],"version-history":[{"count":4,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/posts\/19\/revisions"}],"predecessor-version":[{"id":168,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/posts\/19\/revisions\/168"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/media\/116"}],"wp:attachment":[{"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/media?parent=19"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/categories?post=19"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.hslracing.com\/electronics\/wp-json\/wp\/v2\/tags?post=19"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}