1 files changed, 34 insertions, 0 deletions
diff --git a/firmware/zpu/divisors.py b/firmware/zpu/divisors.py
new file mode 100755
index 000000000..d31bd4dad
--- /dev/null
+++ b/firmware/zpu/divisors.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+
+speeds = (9600, 19200, 38400, 57600, 115200, 230400)
+
+master_clk = 100e6
+wb_clk = master_clk / 2
+
+def divisor(speed):
+    div0 = wb_clk // (speed * 16)
+    div1 = div0 + 1
+    actual0 = actual_speed(div0)
+    actual1 = actual_speed(div1)
+    if abs(actual0 - speed) < abs(actual1 - speed):
+        return div0
+    else:
+        return div1
+
+def actual_speed(divisor):
+    return (wb_clk // divisor) / 16
+
+def doit(speed):
+    div = divisor(speed)
+    actual = actual_speed(div)
+    rel_error = (actual - speed) / speed
+    print "target: %6d  divisor: %6d  actual: %11.4f  %6.3f%%" % (speed, div, actual, rel_error*100)
+
+def main():
+    print "wb_clk = %f" % (wb_clk,)
+    for s in speeds:
+        doit(s)
+
+if __name__ == '__main__':
+    main()
+