Arduino mega 2560 ss pin4/20/2024 Put simply, you can’t use it if you ever want more than one SPI device. But that’s not the most vexing issue you’d have to debug. Just get ready for this to begin with–where you want that SS line may not be where you get that SS line. Where is PORTL?Īs Hao Jiang found in this post about Arduino Mega port mapping, not all ports on the Mega even seem to respond to changes in their respective registers, so unless you’re okay with using pinMode() and digitalWrite() in your SPI code, the SS options are preemptively limited. You’ll need to use an additional pin as an extra SS line, and that pin may not be on the same port. If you’re daisy chaining SPI devices, there’s only one pin 53. This keeps everything cleanly on the same register, but with SPI it may not always work out that way. On the Mega, MOSI (pin 51) is PORTB 2, MISO (pin 50) is PORTB 3, SCK (pin 52) is PORTB 1, and SS (pin 53) is PORTB 0. It follows then that I/O standards on the Arduino are usually grouped into a single port, which is the case on both the Uno and the Mega. Set bit 0 on register PORTB (port pins, port B) Set bit 0 on register DDRB (direction, port B) If you were to want to rapidly switch pin 0 on PORTB on, you would initially set its direction bit high to make it an output, then set its port bit high to bring its voltage high. The pins on the Arduino are divided into ports logically, such as PORTA, PORTB, etc., which can be seen nicely in this diagram. Many SPI devices will use cbi() and sbi() functions to clear and set bits directly on port registers of the Arduino, which has a number of advantages like resulting in smaller code, much faster switching, and the ability to switch multiple pins at the same time. It turns out that CS on 53 is actually more important than you might think when doing daisy chaining, but more on that in a moment. Pull the CS low, then read from MISO, no problems at all. If you attach the bus to pins 51, 50, and 52, then run a chip select (also called slave select, CS, or SS) line to the provided pin 53, this seems to function with no issues. Interestingly, SPI does seem to work fine on the Mega in test cases. While MOSI, MISO, and SCK are on pins 11, 12, and 13 respectively on the Uno, those change to 51, 50, and 52 on the Mega. I initially daisy chained two LTC2400 analog-to-digital modules onto the SPI bus, just like I had them on the Uno, but immediately ran into issues. In theory these devices should handle SPI in the same manner, just with different pins. TL DRCan someone help me wire my ST7789 based 2.While working on a new revision of a project, I moved from an Arduino Uno to an Arduino Mega. I tried moving the SCK/CIPO/COPI/SS pins to the respective SCK/MISO/MOSI/SS pins of the Arduino MEGA, as I thought the Adafruit_ST7789 library could use some reserved pins, #define 'd in the header files somewhere (in my code I only had to reference 3 pins: CS, RST and DC, but had to wire up more to make the screen work), however, this did not work. I did find these 2 diagrams describing the pinout of both of my Arduinos: The screen would now only light up with white light (as it should at the beginning) but it did not display anything. I connected the screen in the exact same way, all the pins I used were the same. The second problem was when I tried to connect the screen (only the display, not touch) to my Arduino MEGA 2560. (RESOLVED: the screen I ordered does not support touch data, thanks u/TDHofstetter) The code would always output either (0,0) or (319,239) (the last pixel on the screen). The display lit up and worked fine, however, this is where I encountered my first issue: I could not make the touch screen work (I got instructions on how to wire it from a few different sources, but this is the only one I could find in my history. After arriving I tested the screen using this tutorial I found (making sure to change the "Adafruit_ST7735" library to "Adafruit_ST7789", but leaving the wiring the same) and an Arduino Uno. I have recently bought this TFT LCD screen from Aliexpress.
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |