6
votes
max7219 chained display showing mirrored text
Since version 3.0 MD_MAX72xx.h no longer supports that definition. Now the hardware type is defined as a parameter on creation (in the "Example" file you are using - not in MD_MAX72xx.h)
#define ...
- 161
3
votes
DHT11's data on MAX7219 reads 0
It turned out that MD_Parola can't handle floats directly. I fixed the problem by converting the floats t and h into strings using dtostrf()
float h = dht.readHumidity();
float t = dht....
- 53
3
votes
Accepted
Scroll Left to Right on MAX7219 Display
To scroll in the opposite direction, change this if statement:
if( --x < len * -8 ) {
x = LEDMATRIX_WIDTH;
}
to this:
if( ++x > LEDMATRIX_WIDTH+len*8 ){
x = 0;
}
x (the start ...
- 16.5k
3
votes
Accepted
MAX7219 powered on via digital pin set to HIGH is not working good (I < 25mA)
After some research I eventually solved my problem, so here's the answer.
Why does it happen?
This LED display draws much more current than I measured on Vcc line between Arduino and display ...
- 302
2
votes
ISR and multiplexing- time required to execute the code in Arduino
(In a comment the asker mentioned they're not sure of the "usual approach", so I've provided this answer to hopefully help clarify)
Here is my code for using a single 595 to drive the columns, and ...
- 168
2
votes
ISR and multiplexing- time required to execute the code in Arduino
I think the code is likely wrong.
the code is called every 10ms, each time refreshing all columns and all rows and then immediately overwriting them all. so you should just see a quick flicker.
the ...
- 2,780
2
votes
max7219 chained display showing mirrored text
Check the configuration in MD_MAX72xx.h file and ensure you have the right module selected.
For example there is a define
#define USE_PAROLA_HW 0
if your hardware is this item then turn off the ...
2
votes
SPI Wiring Confusion
SPI is a communication protocol, you can take advantage of some hardware optimizations by using the pins where that hardware is available or you can do everything by hand using any pin you like, with ...
- 1,271
2
votes
Accepted
Removing spaces between characters in MD_Parola
add this line in the void setup part
P.setCharSpacing(0);
- 36
2
votes
Arduino IDE Doesn't Detect Installed Library Dependency
Just guessing... This looks like a case-sensitivity problem to me:
the MD_MAXPanel library repost a dependency on MD_MAX72xx
(lowercase xx), whereas MD_MAX72XX explicity states its name is
MD_MAX72XX (...
- 44.3k
2
votes
Accepted
Tinyduino I/O line voltage level
Whatever your power supply voltage is. If you run it from 5V you get 5V IO. If you run it from a 3V coin cell you get 3V IO.
- 106k
1
vote
MAX7219 library that can compensate for poorly designed/miswired 8x32 panel?
The issue is minor. It looks like the library was designed for a slightly different matrix display / wiring.
Take a look at the library and it likely maps the input buffer to segment / dot-matrix ...
- 2,780
1
vote
Accepted
MAX7219 with Arduino UNO - LED control doesn't work
OMG, the only problem was a typo in LedController initialisation! I used LedControl lc=LedControl(12,11,10,4); instead for LedControl lc=LedControl(11,12,10,4);. It seems the library has no error ...
- 141
1
vote
DS3231 Clock project shows right date but wrong day
The library seems to be addressing device register 3.
According to the DS3231 datasheet this register has valid values 1-7, with 1 being Sunday.
You have:
dow2str(Clock.getDoW()+1, szMesg, MAX_MESG);
...
- 5,414
1
vote
Accepted
Parola library and DS3231 clock
Your first problem is the definition of the text array:
const char *pc[NUM_ZONES] =
{ "TIME", // This will be replaced by real time its only for logic of rows here
"ROOM",
"SUBJECT",
"...
- 1,331
1
vote
Daisy chaining of multiple blocs of 4x(8x8) MAX7219 matrix
All is OK changing the proposed statement
define HARDWARE_TYPE MD_MAX72XX::PAROLA_HW
to
define HARDWARE_TYPE MD_MAX72XX::FC16_HW
- 13
1
vote
Making a timer accurate to 1 millisecond possible? Using MAX7219 LED
You generally cannot rely on a processor for correct time keeping without a real time clock somewhere in your circuit. However, the best way of doing things at certain times, is to call millis() ...
- 521
1
vote
Accepted
Using an Android bluetooth terminal to change preset states on 8x8 LED matrixes
Your problem is, that you read from the EEBlue serial interface, but you are just echoing it over Serial and don't do anything with it. The display code is only executed, when the commands come ...
- 16.5k
1
vote
MAX7219 and Arduino
Got it somewhat working by changing:
#define HARDWARE_TYPE MD_MAX72XX::FC16_HW
to:
#define HARDWARE_TYPE MD_MAX72XX::ICSTATION_HW
But still a little problem with the last character in a message not ...
- 69
1
vote
How to drive SPI MAX7219 7-segment led module using MCP23S17 extender
The MAX7219 chip is designed to be daisy chained -- connect Dout to the Din of the next MAX7219 (see the No-op Register section in the data sheet). I'm not sure if there is a limit to the number that ...
- 2,120
1
vote
Accepted
How to drive SPI MAX7219 7-segment led module using MCP23S17 extender
I'm not 100% on what you want to do but I have used both the chips you seem to want to do it with.
The MAX7219 can control 8 7Segment displays.
I don't remember it being an SPI device, you just set ...
- 5,637
1
vote
Need help with using LED matrix with pushbuttons
It appears you are attempting to use the hardware UART for both talking to your MAX7221 or MAX7219:
LedControl lc=LedControl(2,1,0,2);
And for talking to, maybe, the SDK's serial monitor:
Serial....
- 7,470
1
vote
Accepted
MAX7219 not behaving as expected
After fiddling around with various Libraries, I came across this one.
MD_MAX72XX
It has all the functionalities that I needed with a good Simple Wiki to get you started.
Also it is simple enough ...
- 137
1
vote
MAX7219 not behaving as expected
Looking at your library source, it seems the number of devices is clamped at 8. This isn't a hard limit imposed by the chip but rather practical design. SPI, especially at high speeds, can get ...
- 2,422
1
vote
MAX7219 not behaving as expected
Have you checked the wiring between matrices and/or swapped modules in case there is a faulty one in the sequence?
- 121
Only top scored, non community-wiki answers of a minimum length are eligible