Added script to check PCC_CLK lock status

This script is used to check the lock bits on the PCC_CLK. It is a downsized version of set_clk.py.
This file is not tested but is likely to works as set_clk.py is used on the laptop.

check_clk_status.py

+'''
+Copyright 2021 Stichting Nederlandse Wetenschappelijk Onderzoek Instituten,
+ASTRON Netherlands Institute for Radio Astronomy
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+ http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+Set PCC_CLK
+
+'''
+import sys
+import time
+sys.path.insert(0,'.')
+import os
+if os.name =="posix":
+    from I2C_serial_pi import *
+else:
+    from I2C_serial import *
+
+I2CBUSNR=1
+sleep_time=0.05
+READ_LOCK = True
+
+CS   = 6
+SCLK = 4
+SDO = 5
+SDI = 7
+
+
+def Read_byte_PLL(reg_address, nof_bytes=1, ADDRESS=0x20 ):
+    #
+    # Read Byte from the ADC
+    #
+    I2C_device = I2C(ADDRESS)
+    I2C_device.bus = I2CBUSNR
+    PLL_rw    = 0x01 # 0 for write, 1 for read
+
+    I2C_device.write_bytes(0x06, 0x2C)
+    data =  ( reg_address << 7 ) + PLL_rw
+
+#    print("write read command")
+
+    bit_array = "{0:{fill}8b}".format(data, fill='0')
+    for bit in bit_array:
+        for clk in range(2):
+            Write_data = 0x02 | (0 << CS) | (clk << SCLK) | ( int(bit) << SDI)
+            I2C_device.write_bytes(0x02, Write_data)
+#            sleep(sleep_time)
+
+#    print("read byte")
+    read_bit = ''
+    for cnt in range(8*nof_bytes):
+        for clk in [0, 1]: # Read after rizing edge
+            Write_data = 0x02 | (clk << SCLK) | ( int(bit) << SDI )
+            I2C_device.write_bytes(0x02, Write_data)
+        ret_ack, ret_value = I2C_device.read_bytes(0x00, 1)
+#        stri= "ret_value = {}".format(int(ret_value,16))
+#        print(stri)
+        if ret_ack:
+            read_bit += str((int(ret_value, 16) >> SDO) & 0x01)
+        else:
+            print("ACK nok")
+    Write_data = 0x02 | (1 << CS) | (0 << SCLK) | (0 << SDI)
+    I2C_device.write_bytes(0x02, Write_data)
+    stri = "Read back at address 0x{0:{fill}2x} result : 0x{1:{fill}2x} ".format(reg_address, int(read_bit, 2), fill='0')
+    print(stri)
+    return read_bit;
+
+
+
+
+if READ_LOCK:
+    ret_value = Read_byte_PLL(0x00, nof_bytes = 1)
+    status_pll = int(ret_value,2)
+    if status_pll == 0x04:
+        print("PLL in lock")
+    elif (status_pll & 0x10) > 0:
+        print("Not Locked --> No 10 MHz ref")
+    else:
+        print("Not locked --> PLL Error")
+