#!/usr/bin/ruby

def add_checksum(packet)
  a = b = 0
  packet[2..-1].each{|v|
    a += v
    b += a
  }
  packet << (a % 0x100)
  packet << (b % 0x100)
end

ubx_class = 0x01
ubx_id = 0x60

add_checksum([0xB5, 0x62, 0x06, 0x01, 0x08, 0x00, ubx_class, ubx_id, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]).each{|v|
  $stderr.print "<#{sprintf('%02X', v)}>"
}