add the devmem2.py and blink files

blink.py

@@ -0,0 +1,14 @@
+#!/usr/bin/python3
+
+import time, os, sys
+
+os.chdir("/sys/class/gpio/")
+os.system("echo {} > export".format(sys.argv[1]))
+os.chdir("gpio{}".format(sys.argv[1]) )
+os.system("echo out > direction")
+for i in range(20):
+  os.system("echo 1 > value")
+  time.sleep(1)
+  os.system("echo 0 > value")
+  time.sleep(0.2)
+

devmem2.py

@@ -0,0 +1,48 @@
+#!/usr/bin/python3
+
+# simply a python3 version of the 'devmem2' program written by Jan-Derk Bakker (2010)
+# this one is written by Pat Beirne <patb@pbeirne.com>
+
+from mmap import mmap
+import os, sys, time, struct
+
+if __name__ == "__main__":
+  if len(sys.argv) == 1:
+    print("devmem2: read/write memory location, version 1.0")
+    print("  python3 version; only operates on 32 bit words (w)")
+    print("  syntax:     devmem2 address [ type [ write-data ]]")
+    sys.exit(1)
+
+  write_mode = False
+  if len(sys.argv) == 4:
+    if sys.argv[2] != 'w':
+      print("error: only w is permitted in the 2nd parameter....32bit word")
+      sys.exit(1)
+    try:
+      write_data = int(sys.argv[3],0)
+    except:
+      print("error: the 3rd parameter must be a number, not {}".format(sys.argv[3]))
+      sys.exit(1)
+    write_mode = True
+  try:
+    address = int(sys.argv[1],0)
+  except:
+    print("error: the 1st parameter must be a number, not {}".format(sys.argv[1]))
+    sys.exit(1)
+
+  # print("got past parameter check")
+
+  with open("/dev/mem","r+b") as m:
+    address_page = address & ~0xFFF
+    address_offset = address & 0xFFF
+    mem = mmap(m.fileno(), 32, offset = address_page)
+    # read 4-byte word....often a requirement on ARM devices
+    read_data = struct.unpack("<L", mem[address_offset: address_offset+4])[0]  
+    print("Value at address {}: {}".format(hex(address),hex(read_data)))
+    if write_mode == False:
+      sys.exit(0)
+    mem[address_offset:address_offset+4] = struct.pack("<L",write_data)
+    read_data = struct.unpack("<L", mem[address_offset: address_offset+4])[0]  
+    print("Written {}; readback {}".format(hex(write_data),hex(read_data)))
+    sys.exit(0)
+