diff --git a/eiger/test/trimbit.py b/eiger/test/trimbit.py
new file mode 100644
index 0000000..1e0d397
--- /dev/null
+++ b/eiger/test/trimbit.py
@@ -0,0 +1,26 @@
+import matplotlib.pyplot as plt
+import numpy as np
+plt.ion()
+
+
+# These are more or less standard dacs, if you see strange effects
+# you might need to tune them 
+dacs = np.array([   0, 2480, 2900, 1400, 4000, 2556,  898,  848,    0,  855, 1100,
+       1100,  982,  895, 2000, 1550,  570,    0], dtype=np.int32)
+
+tb = np.zeros((256,1024), dtype = np.int32)
+
+# Create the desired pattern 
+for row in range(0,256,64):
+    for col in range(0,1024,64):
+        print(f'{row}, {col}')
+        tb[row:row+32, col:col+32] = 63
+
+
+fig, ax = plt.subplots()
+im = ax.imshow(tb)
+
+
+with open('trimbits.sn000', 'wb') as f:
+    dacs.tofile(f)
+    tb.tofile(f)
\ No newline at end of file
diff --git a/eiger/test/trimbits.sn000 b/eiger/test/trimbits.sn000
new file mode 100644
index 0000000..00b968b
Binary files /dev/null and b/eiger/test/trimbits.sn000 differ