Hopiu/rpi-rgb-led-matrix
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o Readme improvements.

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o some TODO updates in gpio.cc
This commit is contained in:
Henner Zeller 2015-07-19 19:52:41 -07:00
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100
README.md
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@ -10,7 +10,7 @@ GNU General Public License Version 2.0 <http://www.gnu.org/licenses/gpl-2.0.txt>
The example code using this library is released in the public domain.
## NOTE the pinout changed on 2015-07-19 to provide more glitch-free output. If you have an existing wiring, provide -DRGB_CLASSIC_PINOUT to the compilation or consider changing the wiring as it provides a much more stable image.
## [PSA: the pinout changed on 2015-07-19 to provide more glitch-free output. If you have an existing wiring, provide -DRGB_CLASSIC_PINOUT to the compilation; better yet, consider changing the wiring as it provides a much more stable image.]
Overview
--------
@ -37,6 +37,9 @@ The Raspberry Pi 2 is faster than older models and sometimes the cabeling can't
speed; check out this [troubleshooting section](#help-some-pixels-are-not-displayed-properly)
what to do.
It is recommended to install an image with a realtime kernel (for instance [this one][emlid-rt])
to minimize a loaded system having an influence on the image quality.
Connection
----------
You need a separate power supply for the panel. There is a connector for that
@ -83,37 +86,40 @@ For reference, this is how the numbering on the Raspberry Pi looks like:
This is the same representation as in the table below, which allows nice visual inspection.
For each of the up to three chains, you have to connect GND, strobe,
clock, OE, A, B, C, D to all of these; you find the positions below (note there are more GND
pins on the Raspberry Pi, but for simplicity, they are left out; The `---` are not connected).
For each of the up to three chains, you have to connect `GND`, `strobe`,
`clock`, `OE-`, `A`, `B`, `C`, `D` to all of these; you find the positions
below (note there are more GND pins on the Raspberry Pi, but for simplicity
(we only need one), they are left out).
Then for each panel, there is a set of (R1, G1, B1, R2, G2, B2) that you have
to connect to the places marked `[1]`, `[2]` and `[3]` for chain 1, 2, and 3.
to connect to the corresponding pins that are marked `[1]`, `[2]` and `[3]` for
chain 1, 2, and 3 below.
To make things quicker to see visually, I've marked each chain with a separate
icon `[1]`=:smile:, `[2]`=:boom: and `[3]`=:droplet:.
icon `[1]`=:smile:, `[2]`=:boom: and `[3]`=:droplet:; signals that go to all chains
are marked with all icons.
Connection | Pin | Pin | Connection
----------------:|:---:|:---:|:-----------
--- | 1 | 2 | ---
:droplet:`[3] G1`| 3 | 4 | ---
:droplet:`[3] B1`| 5 | 6 | GND
strobe | 7 | 8 | `[3] R1` :droplet:
--- | 9 | 10 | ---
clock | 11 | 12 | OE
:smile: `[1] G1`| 13 | 14 | ---
A | 15 | 16 | B
--- | 17 | 18 | C
:smile: `[1] B2`| 19 | 20 | ---
:smile: `[1] G2`| 21 | 22 | D
:smile: `[1] R1`| 23 | 24 | `[1] R2` :smile:
--- | 25 | 26 | `[1] B1` :smile:
--- | 27 | 28 | ---
:boom: `[2] G1`| 29 | 30 | ---
:boom: `[2] B1`| 31 | 32 | `[2] R1` :boom:
:boom: `[2] G2`| 33 | 34 | ---
:boom: `[2] R2`| 35 | 36 | `[3] G2` :droplet:
:droplet:`[3] R2`| 37 | 38 | `[2] B2` :boom:
--- | 39 | 40 | `[3] B2` :droplet:
Connection | Pin | Pin | Connection
---------------------------------:|:---:|:---:|:-----------------------------
- | 1 | 2 | -
:droplet: **[3] G1** | 3 | 4 | -
:droplet: **[3] B1** | 5 | 6 | **GND** :smile::boom::droplet:
:smile::boom::droplet: **strobe** | 7 | 8 | **[3] R1** :droplet:
- | 9 | 10 | -
:smile::boom::droplet: **clock** | 11 | 12 | **OE-** :smile::boom::droplet:
:smile: **[1] G1** | 13 | 14 | -
:smile::boom::droplet: **A** | 15 | 16 | **B** :smile::boom::droplet:
- | 17 | 18 | **C** :smile::boom::droplet:
:smile: **[1] B2** | 19 | 20 | -
:smile: **[1] G2** | 21 | 22 | **D** :smile::boom::droplet:
:smile: **[1] R1** | 23 | 24 | **[1] R2** :smile:
- | 25 | 26 | **[1] B1** :smile:
- | 27 | 28 | -
:boom: **[2] G1** | 29 | 30 | -
:boom: **[2] B1** | 31 | 32 | **[2] R1** :boom:
:boom: **[2] G2** | 33 | 34 | -
:boom: **[2] R2** | 35 | 36 | **[3] G2** :droplet:
:droplet:**[3] R2** | 37 | 38 | **[2] B2** :boom:
- | 39 | 40 | **[3] B2** :droplet:
In the [adapter/](./adapter) directory, there are some boards that make
the wiring task simpler.
@ -131,20 +137,21 @@ that is now all dynamically configurable).
Options:
-r <rows> : Display rows. 16 for 16x32, 32 for 32x32. Default: 32
-P <parallel> : For Plus-models or RPi2: parallel chains. 1..3. Default: 1
-c <chained> : Daisy-chained boards. Default: 1.
-L : 'Large' display, composed out of 4 times 32x32
-p <pwm-bits> : Bits used for PWM. Something between 1..11
-l : Don't do luminance correction (CIE1931)
-D <demo-nr> : Always needs to be set
-d : run as daemon. Use this when starting in
/etc/init.d, but also when running without
terminal (e.g. cron)
-t <seconds> : Run for these number of seconds, then exit.
(if neither -d nor -t are supplied, waits for <RETURN>)
-c <chained> : Daisy-chained boards. Default: 1.
-L : 'Large' display, composed out of 4 times 32x32
-p <pwm-bits> : Bits used for PWM. Something between 1..11
-l : Don't do luminance correction (CIE1931)
-D <demo-nr> : Always needs to be set
-d : run as daemon. Use this when starting in
/etc/init.d, but also when running without
terminal (e.g. cron).
-t <seconds> : Run for these number of seconds, then exit.
(if neither -d nor -t are supplied, waits for <RETURN>)
-b <brightness> : Sets brightness percent. Default: 100.
Demos, choosen with -D
0 - some rotating square
1 - forward scrolling an image
2 - backward scrolling an image
1 - forward scrolling an image (-m <scroll-ms>)
2 - backward scrolling an image (-m <scroll-ms>)
3 - test image: a square
4 - Pulsing color
5 - Grayscale Block
@ -152,8 +159,10 @@ that is now all dynamically configurable).
7 - Conway's game of life (-m <time-step-ms>)
8 - Langton's ant (-m <time-step-ms>)
9 - Volume bars (-m <time-step-ms>)
10 - Evolution of color (-m <time-step-ms>)
11 - Brightness pulse generator
Example:
./led-matrix -d -t 10 -D 1 runtext.ppm
./led-matrix -t 10 -D 1 runtext.ppm
Scrolls the runtext for 10 seconds
To run the actual demos, you need to run this as root so that the
@ -483,6 +492,13 @@ dropped due to its slow speed..
There seems to be a limit in how fast the GPIO pins can be controlled, which
limits the frame-rate.
Fun
---
I am always happy to see users successfully using the software for wonderful things, like this
installation by Dirk in Scharbeutz, Germany:
![](./img/user-action-shot.jpg)
[hub75]: ./img/hub75.jpg
[hub75-arrow]: ./img/hub75-other.jpg
[hub75-idc]: ./img/idc-hub75-connector.jpg
@ -495,5 +511,5 @@ limits the frame-rate.
[sparkfun]: https://www.sparkfun.com/products/12584
[ada]: http://www.adafruit.com/product/1484
[git-submodules]: http://git-scm.com/book/en/Git-Tools-Submodules
[emlid-rt]: http://www.emlid.com/raspberry-pi-real-time-kernel-available-for-download/
[emlid-rt]: http://docs.emlid.com/Downloads/Real-time-Linux-RPi2/
[rt-paper]: https://www.osadl.org/fileadmin/dam/rtlws/12/Brown.pdf

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22
lib/gpio.cc
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@ -15,6 +15,7 @@
#include "gpio.h"
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
@ -22,7 +23,6 @@
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include <assert.h>
// Raspberry 1 and 2 have different base addresses for the periphery
#define BCM2708_PERI_BASE 0x20000000
@ -261,15 +261,25 @@ static void sleep_nanos_rpi_2(long nanos) {
}
/*
TODO hardware timing: more CPU use and less refresh rate than 'regular'
- darker, i.e more setup time in-between (= more dark time) (less current use)
- lower refresh rate
TODO hardware timing: current observation:
- More CPU use and less refresh rate than 'regular' (USE_HARDWARE_PWM_TIMER=0)
- Darker, i.e more setup time in-between (= more dark time) (less current use)
- Lower refresh rate
- The usleep() are annoying. Ideally, we can wait for the pulsing to finish
with some interrupt.
- usleep() in PWM setup is needed to get the registers settled, but it is not
clear what an ideal version would be. Ideally, we never switch the baseline
but rather write to the fifo more bits (but: it is too short and we
shouldn't wait.
- More work needed.
*/
// A PinPulser that uses the PWM hardware to create accurate pulses.
// It only works on GPIO-18 though.
// Based in part on discussion found on
// https://www.raspberrypi.org/forums/viewtopic.php?t=67741&p=494768
//
// TODO: - divider switching is very slow.
class HardwarePinPulser : public PinPulser {
public:
static bool CanHandle(uint32_t gpio_mask) { return gpio_mask == (1 << 18); }
@ -320,6 +330,8 @@ public:
virtual void WaitPulseFinished() {
if (!any_pulse_sent_) return;
// Wait until FIFO is empty.
// TODO(hzeller): this is a very crude way to wait for the result.
// ideally, we could use the interrupt feature to wait for the result.
pwm_reg_[PWM_FIFO] = 0;
while ((pwm_reg_[PWM_STA] & PWM_STA_EMPT1) == 0) {
usleep(1);
@ -358,7 +370,7 @@ private:
pwm_reg_[PWM_CTL] = PWM_CTL_USEF1 | PWM_CTL_MODE1 | PWM_CTL_PWEN1 | PWM_CTL_POLA1;
pwm_reg_[PWM_STA] = -1; // clear status bits.
usleep(1); // TODO: what is a good time here ?
usleep(1); // TODO: what is a good time here ? Are there better ways ?
//for (int i = 0; i < 300; ++i) { asm(""); } // Registers need a while to settle.
last_divider_ = divider;
}