A VFD (Vacuum Fluorescent Display) is an electronic display device that is commonly used for displaying numeric or alphanumeric characters. It is similar to an LCD (Liquid Crystal Display) but uses a different technology to display information. VFD displays are known for their high brightness, high contrast, and wide viewing angle, making them suitable for use in a variety of applications, including digital clocks. Exactly such a clock is described in this video.
I recently acquired a VFD display with a resolution of 256 x 50 dots for a relatively affordable price.
Unfortunately, I could not get a datasheet or any more detailed information from the supplier, except that it is compatible with an STM32 microcontroller, which for me meant that it can be easily connected to other microcontrollers such as Arduino. On the back of the PCB, the display model is marked as GP1287, so based on this information I found a document that shows the pinout of the display and some basic data. However, to create code without the support of libraries is relatively complex.
For that reason, I looked in more detail at the libraries for graphic support of displays, when I discovered that the latest versions of the U8G2 library support exactly this type of VFD display. Now with this kind of support it is quite easy to create code that will use this display. To demonstrate these claims, as the simplest example, I decided to create an NTP clock that retrieves the correct time over the Internet.
Making such a clock is extremely simple and consists of only two components:
- ESP8266 microcontroller board
- and GP1287 VFD display
First I will test the device with a short demo sketch that is an integral part of the library, which demonstrates some of the graphical capabilities
In the code, we only need to enter the credentials of the local Wi-Fi network, and then upload it to the microcontroller. As for this procedure, this time we will not hold back, because it has been described several times in my previous projects, and there are also excellent tutorials on the Internet.
After turning on the device, we need to wait for a certain time while the microcontroller connects to the Wi-Fi network and NTP servers. As seen on the screen, the correct time appears with the largest digits, the date is displayed below it, in the upper right part of the screen there is numerical information about the day of the week, and below it the day of the week.
As I mentioned before, the information on the display is clearly visible from all angles thanks to the specific way of radiating light, both in daylight and at night.
This is the simplest example that basically shows how to connect the display to an ESP8266 microcontroller, but it can be connected to an Arduino in a similar way by changing the number of pins when defining it in the U82G library.
Finally, the device is installed in a suitable box made of PVC material with a thickness of 5 mm and covered with colored self-adhesive wallpaper.
Update:
Due to the relatively high consumption of the display, it is preferable to power it through the power connector of the display itself, which is shown in the picture.
/*
This is an example file for using the time function in ESP8266 or ESP32 tu get NTP time
It offers two functions:
- getNTPtime(struct tm * info, uint32_t ms) where info is a structure which contains time
information and ms is the time the service waits till it gets a response from NTP.
Each time you cann this function it calls NTP over the net.
If you do not want to call an NTP service every second, you can use
- getTimeReducedTraffic(int ms) where ms is the the time between two physical NTP server calls. Betwwn these calls,
the time structure is updated with the (inaccurate) timer. If you call NTP every few minutes you should be ok
The time structure is called tm and has teh following values:
Definition of struct tm:
Member Type Meaning Range
tm_sec int seconds after the minute 0-61*
tm_min int minutes after the hour 0-59
tm_hour int hours since midnight 0-23
tm_mday int day of the month 1-31
tm_mon int months since January 0-11
tm_year int years since 1900
tm_wday int days since Sunday 0-6
tm_yday int days since January 1 0-365
tm_isdst int Daylight Saving Time flag
because the values are somhow akwardly defined, I introduce a function makeHumanreadable() where all values are adjusted according normal numbering.
e.g. January is month 1 and not 0 And Sunday or monday is weekday 1 not 0 (according definition of MONDAYFIRST)
Showtime is an example on how you can use the time in your sketch
The functions are inspired by work of G6EJD ( https://www.youtube.com/channel/UCgtlqH_lkMdIa4jZLItcsTg )
*/
#ifdef ESP8266
#include <ESP8266WiFi.h>
#else
#include <WiFi.h>
#endif
#include <time.h>
#include <U8x8lib.h>
#define mySSID "TEST"
#define myPASSWORD "TEST"
const char* ssid = mySSID; //from credentials.h file
const char* password = myPASSWORD; //from credentials.h file
const char* NTP_SERVER = "ch.pool.ntp.org";
const char* TZ_INFO = "GMT+0BST-1,M3.5.0/01:00:00,M10.5.0/02:00:00"; // enter your time zone (https://remotemonitoringsystems.ca/time-zone-abbreviations.php)
tm timeinfo;
time_t now;
long unsigned lastNTPtime;
unsigned long lastEntryTime;
//U8X8_SSD1306_128X64_NONAME_SW_I2C u8x8(/* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE); // OLEDs without Reset of the Display
//U8G2_GP1287AI_256X50_1_4W_SW_SPI u8g2(U8G2_R0, /* clock=*/ 0, /* data=*/ 2, /* cs=*/ 14, /* dc=*/ 4, /* reset=*/ 16); // Za ESP8266 Node mcu {CLK-D3, CS-D5, DATA-D4, RESET-D0}
U8X8_GP1287AI_256X50_4W_SW_SPI u8x8(/* clock=*/ 0, /* data=*/ 2, /* cs=*/ 14, /* dc=*/ 4, /* reset=*/16);
void setup()
{
u8x8.begin();
Serial.begin(115200);
Serial.println("\n\nNTP Time Test\n");
WiFi.begin(ssid, password);
Serial.print("Connecting to network");
int counter = 0;
while (WiFi.status() != WL_CONNECTED)
{
delay(200);
if (++counter > 100)
ESP.restart();
Serial.print( "." );
}
Serial.println("\nWiFi connected\n\n");
configTime(0, 0, NTP_SERVER);
// See https://github.com/nayarsystems/posix_tz_db/blob/master/zones.csv for Timezone codes for your region
setenv("TZ", TZ_INFO, 1);
if (getNTPtime(10))
{
// wait up to 10sec to sync
}
else
{
Serial.println("Time not set");
ESP.restart();
}
showTime(&timeinfo);
lastNTPtime = time(&now);
lastEntryTime = millis();
}
void loop()
{
getNTPtime(10);
showTime(&timeinfo);
delay(1000);
}
bool getNTPtime(int sec)
{
{
uint32_t start = millis();
do
{
time(&now);
localtime_r(&now, &timeinfo);
delay(10);
} while (((millis() - start) <= (1000 * sec)) && (timeinfo.tm_year < (2016 - 1900)));
if (timeinfo.tm_year <= (2016 - 1900))
return false; // the NTP call was not successful
Serial.print("Time Now: ");
Serial.println(now);
}
return true;
}
void showTime(tm *localTime)
{
//print to serial terminal
Serial.print(localTime->tm_mday);
Serial.print('/');
Serial.print(localTime->tm_mon + 1);
Serial.print('/');
Serial.print(localTime->tm_year - 100);
Serial.print('-');
Serial.print(localTime->tm_hour);
Serial.print(':');
Serial.print(localTime->tm_min);
Serial.print(':');
Serial.print(localTime->tm_sec);
Serial.print(" Day of Week ");
Serial.println(localTime->tm_wday);
Serial.println();
//display on OLED
char time_output[30];
u8x8.setFont(u8x8_font_inb21_2x4_f);
u8x8.setCursor(1,0);
sprintf(time_output, "%02d:%02d:%02d", localTime->tm_hour, localTime->tm_min, localTime->tm_sec);
u8x8.print(time_output);
u8x8.setFont(u8x8_font_8x13B_1x2_f);
u8x8.setCursor(5,4);
sprintf(time_output, "%02d/%02d/%02d", localTime->tm_mday, localTime->tm_mon + 1, localTime->tm_year - 100);
u8x8.print(time_output);
u8x8.setCursor(18,4);
u8x8.print("Day of Week:");
u8x8.setCursor(30,4);
u8x8.print(localTime->tm_wday);
u8x8.setCursor(22,1); //(x,Y)
u8x8.print(getDOW(localTime->tm_wday));
}
char * getDOW(uint8_t tm_wday)
{
switch(tm_wday)
{
case 1:
return "Monday";
break;
case 2:
return "Tuesday";
break;
case 3:
return "Wednesday";
break;
case 4:
return "Thursday";
break;
case 5:
return "Friday";
break;
case 6:
return "Saturday";
break;
case 7:
return "Sunday";
break;
default:
return "Error";
break;
}
}
