pyfastservo adc: Add mmcm rst after ADC is rst

fast-servo/pyfastservo/adc.py

@@ -17,7 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
-
+import time
 import spidev
 from pyfastservo.common import (
     ADC_AFE_CTRL_ADDR,
@@ -78,13 +78,21 @@ def read_frame():
 def perform_bitslip():
     for i in range(4):
         current_frame = read_frame()
-        if current_frame != 0x0C:
+        if current_frame & 0x0F != 0x0C:
             print(f"Performing bitslip (iteration: {i}). Current frame: 0x{current_frame:02x}")
             write_to_memory(ADC_BITSLIP_ADDR, 1)
         else:
             print(f"No bitslip required; Current frame: 0x{current_frame:02x}")
             return
 
+def mmcm_rst():
+    curr_cfg = read_from_memory(ADC_AFE_CTRL_ADDR, 1)[0] & 0x0F
+    write_to_memory(ADC_AFE_CTRL_ADDR, 0x10 | curr_cfg) # Reset MMCM
+    write_to_memory(ADC_AFE_CTRL_ADDR, 0x00 | curr_cfg) # Release MMCM Reset
+    while not(read_frame() & 0x10):
+        print(f"Waiting for MMCM to lock")
+        time.sleep(0.001)
+    
 def find_edge():
     prev_frame = read_frame()
     for tap_delay in range(32):
@@ -141,6 +149,9 @@ def configure_ltc2195():
             0x04: test_pattern & 0xFF
         })
 
+        # ADC software reset put its PLL to sleep momentarily. Thus, MMCM needs to be reset as well.
+        mmcm_rst()
+        
         # Performing Word Align
         perform_bitslip()
         find_edge()