matrix77:
Salve e grazie per il tuo intervento,
Scusa, ma non ho molta dimestichezza con questo driver e pensavo rimanesse spento senza comunicazione, quindi in pratica multiplexa in base ad un suo valore di default?
Il MAX7219 per tener spento i Display li tiene polarizzati in modo inverso.
dal datasheet:
Shutdown Mode
When the MAX7219 is in shutdown mode, the scan oscillator is halted, all segment current sources are pulled to ground, and all digit drivers are pulled to V+, thereby blanking the display. ... Data in the digit and control registers remains unaltered. Shutdown can be used to save power or as an alarm to flash the display by successively entering and leaving shutdown mode. ..
Initial Power-Up
On initial power-up, all control registers are reset, the display is blanked, and the MAX7219/MAX7221 enter shutdown mode. Program the display driver prior to display use. Otherwise, it will initially be set to scan one digit, it will not decode data in the data registers, and the intensity register will be set to its minimum value.
Si entra/ esce dal shutdown mode resettando / settando il bit D0 del Shutdown Register (0xXC)
Ciao Uwe