From 07493b94b141506e051b0adb9f68132ebfc583c0 Mon Sep 17 00:00:00 2001
From: Chris Xiong <chirs241097@gmail.com>
Date: Thu, 8 Nov 2018 19:47:52 +0800
Subject: Added the max7219 stuff.

---
 rpi/max7219/max7219.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 rpi/max7219/max7219.c

(limited to 'rpi/max7219/max7219.c')

diff --git a/rpi/max7219/max7219.c b/rpi/max7219/max7219.c
new file mode 100644
index 0000000..33a7fed
--- /dev/null
+++ b/rpi/max7219/max7219.c
@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+#include <time.h>
+#include <wiringPi.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "max7219.h"
+
+#define wait nanosleep(&cl,NULL)
+const struct timespec cl={0,10};
+/*
+ * _sendpacket(d)
+ * sends a 16 bit packet to the data line.
+ * for internal usage only.
+ */
+void _sendpacket(unsigned short d)
+{
+	unsigned char i;
+	for(i=16;i>0;--i)
+	{
+		unsigned short mask=1<<(i-1);
+		digitalWrite(P_CLK,0);wait;
+		digitalWrite(P_DATA,(d&mask)?1:0);
+		wait;digitalWrite(P_CLK,1);wait;
+	}
+}
+/*
+ * max7219_send(r,d,chip)
+ * sets the value of register #d in chip #chip to d.
+ * chips are 0-indexed. chip=-1 means send to all chips.
+ */
+void max7219_send(unsigned char r,unsigned char d,int chip)
+{
+	digitalWrite(P_CS,0);wait;
+	for(int i=0;i<NCHIPS;++i)
+	_sendpacket(chip==-1||i+chip==NCHIPS-1?(r<<8)|d:0);
+	digitalWrite(P_CS,1);wait;
+}
+/*
+ * max7219_batch(d)
+ * sends a batch of data to the chips. each element in d
+ * is a register-data pair. length of d should equal to
+ * the number of chips.
+ * the first chip receives the first data pair,
+ * the second chip receives the second one etc.
+ */
+void max7219_batch(unsigned short *d)
+{
+	digitalWrite(P_CS,0);wait;
+	for(int i=0;i<NCHIPS;++i)
+	_sendpacket(d[NCHIPS-1-i]);
+	digitalWrite(P_CS,1);wait;
+}
+/*
+ * max7219_init()
+ * initialize all chips, putting them into matrix mode.
+ */
+void max7219_init()
+{
+	wiringPiSetup();
+	pinMode(P_DATA,OUTPUT);
+	pinMode(P_CS,OUTPUT);
+	pinMode(P_CLK,OUTPUT);
+	max7219_send(SCAN_LIMIT,7,-1);
+	max7219_send(DECODE_MODE,0,-1);
+	max7219_send(DISPLAY_TEST,0,-1);
+	max7219_send(INTENSITY,1,-1);
+	max7219_send(SHUTDOWN,1,-1);
+}
+/*
+ * max7219_deinit(clear)
+ * putting all chips into sleep, optionally clearing
+ * all the registers when `clear` is set
+ */
+void max7219_deinit(int clear)
+{
+	max7219_send(SHUTDOWN,0,-1);
+	if(clear)
+	for(int i=0;i<8;++i)
+		max7219_send(i+1,0,-1);
+}
-- 
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