commit b746a9907c1484672c1e9eaa65d90f87639ef307
Author: Thomas Klaehn <tkl@blackfinn.de>
Date:   Tue Jan 16 20:24:01 2018 +0100

    relay-switch: Initial commit
    
    Signed-off-by: Thomas Klaehn <tkl@blackfinn.de>

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..20dcf3d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+.vscode/
+build/
+
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..875177b
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,21 @@
+
+DEPENDENCIES := -lpthread -lrt
+CFLAGS := -Wall -Wextra -Iftdi
+
+CC ?= gcc
+
+BUILDDIR := build
+APP = $(BUILDDIR)/relay-switch
+
+all: $(APP)
+
+$(APP): src/main.c
+	@mkdir -p $(BUILDDIR)
+	$(CC) src/main.c -o $(APP) $(CFLAGS) -lftdi $(DEPENDENCIES)
+
+clean:
+	-rm -f $(APP)
+
+install: all
+	install -m 755 $(APP) /usr/local/bin/
+	install -m 644 udev/* /etc/udev/rules.d/
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..ae799af
--- /dev/null
+++ b/README.md
@@ -0,0 +1,32 @@
+# RELAY
+
+Switch 4 channel relay (QY15).
+
+## Prerequisites
+
+* libftdi-dev
+
+## Build
+
+```bash
+make all
+```
+
+## Install
+
+```bash
+make install
+```
+
+## Execute
+
+```bash
+relay-switch -r [1..4] -s [0..1]
+```
+
+with:
+
+```bash
+r: relay
+s: state
+```
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..8172b47
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,87 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <ftdi.h>
+
+#define RELAY_1 1
+#define RELAY_2 2
+#define RELAY_3 3
+#define RELAY_4 4
+
+int main(int argc, char **argv)
+{
+    struct ftdi_context *ftdi;
+    int f, opt;
+    unsigned int relay = 0, state = 0;
+    unsigned char buf[1];
+    int retval = 0;
+
+    openlog("relay_switch", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);
+
+    while((opt = getopt(argc, argv, "r:s:")) != -1) {
+        switch(opt) {
+        case 'r':
+            relay = atoi(optarg);
+            if((relay != RELAY_1) && (relay != RELAY_2) && (relay != RELAY_3) && (relay != RELAY_4)) {
+                syslog(LOG_ERR, "Invalid relay choosen (%d). Choose one of [1..4].\n", relay);
+                return 1;
+            }
+            break;
+        case 's':
+            state = atoi(optarg);
+            if((state != 0) && (state != 1)) {
+                syslog(LOG_ERR, "Invalid state choosen (%d). Choose one of [0/1].\n", state);
+                return 1;
+            }
+            break;
+        }
+    }
+
+    if ((ftdi = ftdi_new()) == 0)
+    {
+        syslog(LOG_ERR, "ftdi_new failed\n");
+        return EXIT_FAILURE;
+    }
+
+    f = ftdi_usb_open(ftdi, 0x0403, 0x6001);
+
+    if (f < 0 && f != -5) {
+        syslog(LOG_ERR, "unable to open ftdi device: %d (%s)\n", f, ftdi_get_error_string(ftdi));
+        retval = 1;
+        goto done;
+    }
+
+    f = ftdi_set_bitmode(ftdi, 0xFF, BITMODE_BITBANG);
+    if(f < 0) {
+        syslog(LOG_ERR, "unable to set bit bang mode: %d (%s)\n", f, ftdi_get_error_string(ftdi));
+        retval = 1;
+        goto done;
+    }
+
+    f = ftdi_read_data(ftdi, buf, 1);
+    if(f < 0) {
+        syslog(LOG_ERR, "unable to readfrom ftdi device: %d (%s)\n", f, ftdi_get_error_string(ftdi));
+        retval = 1;
+        goto done;
+    }
+
+    if(state == 1) {
+        buf[0] |= (char)(1 << (relay - 1));
+    }
+    else {
+        buf[0] &= ~(char)(1 << (relay - 1));
+    }
+
+    f = ftdi_write_data(ftdi, buf, 1);
+    if(f < 0) {
+        syslog(LOG_ERR, "write failed for 0x%x, error %d (%s)\n",buf[0], f, ftdi_get_error_string(ftdi));
+    }
+
+    ftdi_usb_close(ftdi);
+done:
+    ftdi_free(ftdi);
+    closelog();
+
+    return retval;
+}
diff --git a/udev/90-ftdi.rules b/udev/90-ftdi.rules
new file mode 100644
index 0000000..ec02adb
--- /dev/null
+++ b/udev/90-ftdi.rules
@@ -0,0 +1 @@
+ATTR{idVendor}=="0403", ATTR{idProduct}=="6001", MODE="0666"