Features
(4) MAX7219 8 digits, 7 Segment display modules
32 digits
Can display decimal, hex values, some text values
Each display has 8 of 7 segment LED displays
Uses "Blue" LED cards
Rev 1 has 3.3V interface operation (J1)
3.3V to 5V Level shifter
Requires both 3.3V and 5V power supplies
8 pin connector
Rev 2 has 3.3V signal levels J1 (as above) or 5V signal levels (adds J2)
Only requires 5V for 5V operation
Level translator can still be installed but right connector must be used
95x95mm ODAS form factor
(4) 6-32 mounting holes
Connectors
Only 1 of the 2 connectors J1 or J2 can be used at a time
J1 Connector
3.3V signal level
5V power to LEDs
1x8 right angle header mounted on rear of card
GND
GND
DOUT
CLK
CS
DIN
+3.3V
+5V
J2 (Rev 2 and higher)
+5V
DIN
CS
CLK
DOUT
GND
Programming
Arduino Programming
Arduino Drivers
Arduino Example Code
LBMAX7219X4_ADDR
Runs on Arduino in a Box
3.3V signals level
Also requires 5V for LEDs
5V on Arduino in a Box] DC Power Jack
5V picked off VFILT jack
LBMAX7219X4_ADDR
void writeHexDigit(uint8_t rowVal, uint8_t colVal, uint8_t digitVal) - Write Hexadecimal digit to location
8 columns, 4 rows
rowVal = 0 is top row in display
colVal = 0 = left character
LBMAX7219X4_ADDR_5V
Same as LBMAX7219X4_ADDR
Runs on 5V Arduino UNO
LBMAX7219X4_ADDR_5V
void writeHexDigit(uint8_t rowVal, uint8_t colVal, uint8_t digitVal) - Write Hexadecimal digit to location
8 columns, 4 rows
rowVal = 0 is top row in display
colVal = 0 = left character
LBMAX7219X4
LBMAX7219X4
Displays Land-Boards channel intro video across the LEDs on 4 rows of 8-digits MAX7219X4 card
"LAND-" (first line)
"BOARDS" (second line)
"PRESENTS" (third line)
"CARDS...", "AND CODE" (4th line)
CircuitPython Programming
class adafruit_max7219.bcddigits.BCDDigits(spi: SPI, cs: DigitalInOut, nDigits: int = 1)[source]
Basic support for display on a 7-Segment BCD display controlled by a Max7219 chip using SPI.
Parameters
spi (SPI) – an spi busio or spi bitbangio object
cs (DigitalInOut) – digital in/out to use as chip select signal
nDigits (int) – number of led 7-segment digits; default 1; max 8
VHDL Code
instance: MAX7219
generic map(
devices => 2,
intensity => (16#1#, 16#3#)
)
port map (
clk => clock,
data_vector => x"FEDCBA9876543210",
clk_out => MAX7219_CLK,
data_out => MAX7219_DATA,
load_out => MAX7219_LOAD,
reset_n => globalResetN
);
Test
Test single 8-digit modules
Test MAX7219X4 card with (4) 8-digit modules
Test J1 (Rev 1 or Rev 2 or higher)
Test J2 (Rev 2 and higher)
Test Single MAX7219 Modules
SenShld
Desc
MAX J1
Color
VCC
VCC
1
RED
GND
GND
2
BLK
D12
DATAIN
3
WHT
D10
CS
4
BRN
D11
CLK
5
YEL
Test MAX7219X4 Card 3.3V
Signal
AiB
MAX7219X4
Signal
Color
GND
J5-25
J1-1
GND
BLK
D10
J5-21
J1-5
CS
WHT
D11
J5-19
J1-4
CLK
YEL
D12
J5-17
J1-6
DIN
BLU
+3.3V
J5-1
J1-7
+3.3V
RED
VFILT
J9-1
J1-8
5V
ORG
Run Demo code
Displays 0-7, 8-F twice
Displays all 8's
Test MAX7219X4 Card 5V
Signal
Shield
MAX7219X4
Signal
Color
GND
D12-S
J2-6
GND
BLK
D10
D10-S
J2-3
CS
BRN
D11
D11-S
J2-4
CLK
YEL
D12
D12-3
J2-2
DIN
WHT
5V
D12-V
J2-1
5V
RED
Run Demo code
Displays 0-7, 8-F twice
Displays all 8's
"Red" Modules
Incompatible pinouts
Do not work with this card
Flipped from blue modules
Mechanicals
Revision History
Rev 2
Add 5V interface connector - J2
Card can be driven from one of the two interfaces
5V interface does not require 3.3V
Tested / works
+5V
DIN
CS
CLK
DOUT
GND
Rev 1
Tested/works
Requires 3.3V power and signal levels
Requires 5V power
Assembly Sheet