Arduino Uno and library MD_MAX72xx [SOLVED]

Hello,

I’m trying to test my Uno board and 8x8 led matrix with the MD_MAX72xx_HW_Mapper example of the library.

My hardware and my wiring is good, as I can run some sketches of the LedControlMS library
before. (so I changed the pin assignement in the MD_MAX72xx_HW_Mapper example)

The serial monitor show me this :

߸⸮BW⸮Cl<RVZJ⸮0O⸮@E\⸮Gr0⸮B0
n⸮G⸮⸮SR⸮B⸮⸮⸮Rb2CN4jFX ⸮B⸮
⸮C%BZA⸮
T⸮⸮⸮QBGOBҀV⸮⸮r⸮⸮1B⸮\⸮Җ⸮ӑM⸮⸮⸮GCVe
]⸮⸮⸮⸮⸮⸮BABC⸮S⸮
x⸮Q]⸮⸮B⸮C
YG⸮aF⸮BBA⸮FB⸮PT@ ⸮4FAB⸮G0C⸮rRQe

What could it be ?

a sketch like this

void setup() {
  Serial.begin(9600);
}

void loop() {
    Serial.println("Hello world");
    delay(2000); // wait two seconds
}

output me a good "hello world"

Make sure the baud rate menu in the bottom right corner of Serial Monitor matches the setting in the Serial.begin() statement of your code.

Hahaha Thanks !

Newbie question !