diff --git a/src/.gitignore b/src/.gitignore
new file mode 100644
index 0000000..e64bdbf
--- /dev/null
+++ b/src/.gitignore
@@ -0,0 +1 @@
+counter
diff --git a/src/LS7366R.c b/src/LS7366R.c
new file mode 100644
index 0000000..7322449
--- /dev/null
+++ b/src/LS7366R.c
@@ -0,0 +1,41 @@
+#include <wiringPi.h>
+#include <wiringPiSPI.h>
+#include <stdint.h>
+
+#include "LS7366R.h"
+
+
+void ls7366rWriteCmd(uint8_t c) {
+  uint8_t buf[1];
+  buf[0] = c;
+  wiringPiSPIDataRW(SPI_CHAN, buf, 1);
+}
+
+void ls7366rWriteCmdData(uint8_t c, uint8_t d) {
+  uint8_t buf[2];
+  buf[0] = c;
+  buf[1] = d;
+  wiringPiSPIDataRW(SPI_CHAN, buf, 2);
+}
+
+uint8_t ls7366rRead8(uint8_t c) {
+  uint8_t buf[2];
+  buf[0] = c;
+  wiringPiSPIDataRW(SPI_CHAN, buf, 2);
+  return buf[1];
+}
+
+uint32_t ls7366rRead32(uint8_t c) {
+  uint8_t buf[5];
+  buf[0] = c;
+  wiringPiSPIDataRW(SPI_CHAN, buf, 5);
+  uint32_t r = ((uint32_t)buf[1] << 24) | ((uint32_t)buf[2] << 16) | ((uint32_t)buf[3] << 8) | ((uint32_t)buf[4]);
+  return r;
+}
+
+
+void ls7366rInit() {
+  ls7366rWriteCmd(CMD_CLR | REG_STR);
+  ls7366rWriteCmd(CMD_CLR | REG_CNTR);
+  ls7366rWriteCmdData(CMD_WR | REG_MDR0, MDR0_ILO);
+}
diff --git a/src/LS7366R.h b/src/LS7366R.h
new file mode 100644
index 0000000..fdf4fd2
--- /dev/null
+++ b/src/LS7366R.h
@@ -0,0 +1,63 @@
+#ifndef _LS7366R_H_
+#define _LS7366R_H_
+
+#include <stdint.h>
+
+
+const uint8_t REG_MDR0 = 0b00001000;
+const uint8_t REG_MDR1 = 0b00010000;
+const uint8_t REG_DTR  = 0b00011000;
+const uint8_t REG_CNTR = 0b00100000;
+const uint8_t REG_OTR  = 0b00101000;
+const uint8_t REG_STR  = 0b00110000;
+
+const uint8_t CMD_CLR  = 0b00000000;
+const uint8_t CMD_RD   = 0b01000000;
+const uint8_t CMD_WR   = 0b10000000;
+const uint8_t CMD_LOAD = 0b11000000;
+
+const uint8_t STR_CY   = 0b10000000;
+const uint8_t STR_BW   = 0b01000000;
+const uint8_t STR_CMP  = 0b00100000;
+const uint8_t STR_IDX  = 0b00010000;
+const uint8_t STR_CEN  = 0b00001000;
+const uint8_t STR_PLS  = 0b00000100;
+const uint8_t STR_UD   = 0b00000010;
+const uint8_t STR_S    = 0b00000001;
+
+const uint8_t MDR0_NOQ = 0b00000000;
+const uint8_t MDR0_Q1  = 0b00000001;
+const uint8_t MDR0_Q2  = 0b00000010;
+const uint8_t MDR0_Q4  = 0b00000011;
+const uint8_t MDR0_FRC = 0b00000000;
+const uint8_t MDR0_SCC = 0b00000100;
+const uint8_t MDR0_RLC = 0b00001000;
+const uint8_t MDR0_MNC = 0b00001100;
+const uint8_t MDR0_DI  = 0b00000000;
+const uint8_t MDR0_ILC = 0b00010000;
+const uint8_t MDR0_IRC = 0b00100000;
+const uint8_t MDR0_ILO = 0b00110000;
+const uint8_t MDR0_AI  = 0b00000000;
+const uint8_t MDR0_SI  = 0b01000000;
+const uint8_t MDR0_FC1 = 0b00000000;
+const uint8_t MDR0_FC2 = 0b10000000;
+
+const uint8_t MDR1_4CM = 0b00000000;
+const uint8_t MDR1_3CM = 0b00000001;
+const uint8_t MDR1_2CM = 0b00000010;
+const uint8_t MDR1_1CM = 0b00000011;
+const uint8_t MDR1_EC  = 0b00000000;
+const uint8_t MDR1_DC  = 0b00000100;
+const uint8_t MDR1_F_IDX = 0b00010000;
+const uint8_t MDR1_F_CMP = 0b00100000;
+const uint8_t MDR1_F_BW  = 0b01000000;
+const uint8_t MDR1_F_CY  = 0b10000000;
+
+void ls7366rWriteCmd(uint8_t c);
+void ls7366rWriteCmdData(uint8_t c, uint8_t d);
+uint8_t ls7366rRead8(uint8_t c);
+uint32_t ls7366rRead32(uint8_t c);
+void ls7366rInit();
+
+
+#endif // _LS7366R_H_
\ No newline at end of file
diff --git a/src/Makefile b/src/Makefile
new file mode 100644
index 0000000..f12cb5b
--- /dev/null
+++ b/src/Makefile
@@ -0,0 +1,17 @@
+CC=gcc
+
+CFLAGS=-Wall
+LDFLAGS=-lwiringPi
+
+counter:	counter.o LS7366R.o
+	$(CC) -o $@ $(LDFLAGS) $^
+
+.c.o:
+	$(CC) $(CFLAGS) -c $<
+
+.PHONY: all
+all:	counter
+
+.PHONY: clean
+clean:
+	-rm -f *.o counter
diff --git a/src/counter.c b/src/counter.c
new file mode 100644
index 0000000..ba1efed
--- /dev/null
+++ b/src/counter.c
@@ -0,0 +1,81 @@
+#include <wiringPi.h>
+#include <wiringPiSPI.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <pthread.h>
+
+#include "LS7366R.h"
+
+const int CTRL_OUT = 16;
+const int INTR_IN  = 19;
+const int SPI_CHAN = 0;
+const int SPI_SPEED = 1000000;
+
+
+uint32_t ec = 0;
+uint32_t counter = 0;
+uint32_t diff = 0;
+
+pthread_mutex_t counterMutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_mutex_t eventMutex = PTHREAD_MUTEX_INITIALIZER;
+pthread_cond_t eventSignal = PTHREAD_COND_INITIALIZER;
+
+
+void isr() {
+  static uint32_t lastCounter = 0;
+
+  uint32_t currentCounter = read32(CMD_RD | REG_OTR);
+
+  pthread_mutex_lock(&counterMutex);
+  diff = currentCounter - lastCounter;
+  counter = currentCounter;
+  ec++;
+  pthread_mutex_unlock(&counterMutex);
+
+
+  lastCounter = currentCounter;
+  
+  pthread_mutex_lock(&eventMutex);
+  pthread_cond_signal(&eventSignal);
+  pthread_mutex_unlock(&eventMutex);
+}
+
+void init() {
+  wiringPiSetupGpio();
+
+  wiringPiSPISetup(SPI_CHAN, SPI_SPEED);
+
+  pinMode(CTRL_OUT, OUTPUT);
+  digitalWrite(CTRL_OUT, 0);
+
+  pinMode(INTR_IN, INPUT);
+  wiringPiISR(INTR_IN, INT_EDGE_RISING, isr);
+}
+
+int main (void) {
+  static uint32_t lastDiff = 0;
+  uint32_t my_ec = 0;
+  uint32_t my_counter = 0;
+  uint32_t my_diff = 0;
+
+  init();
+  initCounter();
+
+  while (1) {
+    pthread_mutex_lock(&eventMutex);
+    pthread_cond_wait(&eventSignal, &eventMutex);
+    pthread_mutex_unlock(&eventMutex);
+
+    pthread_mutex_lock(&counterMutex);
+    my_ec = ec;
+    my_counter = counter;
+    my_diff = diff;
+    pthread_mutex_unlock(&counterMutex);
+
+    if (my_diff != lastDiff) {
+      lastDiff = my_diff;
+      double f = 1.0 / (((double) my_diff) / 1000000.0);
+      printf("%d %d %d %f\n", my_ec, my_counter, my_diff, f);
+    }
+  }
+}
\ No newline at end of file