Scrolling text on Oscilloscope (ONLY ONE COMPONENT)
Scritte scorrevoli su oscilloscopio (UN SOLO COMPONENTE)


ef140avi di robotop

Scritte a scorrimento su oscilloscopio con un SOLO componente, il micro PIC16F628A. I caratteri da visualizzare vengono memorizzati in EEPROM (codici ASCII da 0x20 a 0x5F cioè numeri, lettere maiuscole e caratteri speciali). La prima locazione di EEprom con il valore 0xFF è considerata la fine del testo scorrevole. L’ultima locazione di EEPROM (indirizzo 0x7F) contiene la velocità di scorrimento (n * 20 mS). La configuration word per questa applicazione (locazione 0x2007) vale 0x3F34. Una volta programmato il micro tramite il connettore ICSP, cortocircuitare i pin VDD e VPP con un ponticello (reset collegato a Vdd). L’oscilloscopio andrà settato per asse X a 2 mS/div e asse Y 1V/div. I caratteri visualizzati in un’unica schermata sono 10.

Il file disponibile per il download ef140.zip contiene il file oggetto .hex per programmare il micro ed il file sorgente main.c.

:: Scrolling text on oscilloscope, built with only one component: the Microchip PIC16F628A. The characters to be displayed are stored in EEPROM (ascii codes from 0x20 to 0x5f so numbers, capital letters and special characters). The first Eeprom location with 0xFF value is considered as end of text. The last Eeprom location (addr 0x7F) contains the scrolling speed in 20mS steps. The configuration word for this application (address 0x2007) is 0x3F34. After programming the micro via the ICSP connector, place a jumper between the pins VDD and VPP (reset input tied to Vdd). The oscilloscope will be set for 2mS/div on X axis and 1V/div on Y axis. One full screen contains 10 characters.

The downloadable file ef140.zip contains the object file (Hex) to program the micro and the main.c source file.

*** added 4 Sept 2009 *** Note:
When programming the micro, verify the configuration word (0x3F34) and remember that you MUST write some character to earom memory ; try with this data starting from earom address 0x00 : 0x49 0x54 0x20 0x57 0x4F 0x52 0x4B 0x53 0x20 0x41 0x54 0x20 0x45 0x4E 0x44 0xFF then write at address 0x7F: 0x0A (that’s decimal 10 * 20 mS scrolling speed). If the scrolling speed is too fast, increment the number in location 0x7F.
May be trigger level adjustment will be needed on the oscilloscope, in order to synchronize the scrolling text. The text field is preceded by a single sync pulse. Adjust the trigger level to make the text field stable. In many oscilloscopes, this will be done automatically, but some old one (like mine) will require a manual level adjust. Note that this circuit DOESN’T WORK with some digital oscilloscopes, due to the dot’s visualization method.

ef140sch The full schematic
ef140pic The prototype