Added jump to bootloader

[pyshared.git] / bus_pirate.py

diff --git a/bus_pirate.py b/bus_pirate.py
index 4ef9c61d4eacf79612be535156477e553b4d770b..52a1c5c1b759fc2f8f20fd633b0fbbbc9ec4f3f9 100644 (file)
--- a/bus_pirate.py
+++ b/bus_pirate.py
@@ -64,6 +64,29 @@ class BP:
                v = struct.unpack(">h", s)
                return v[0]/1024.0*6.6
 
+       # http://codepad.org/qtYpZmIF
+       def pwm(self, freq, duty_cycle):
+               lPrescaler = {0:1, 1:8 , 2:64, 3:256}
+               Fosc = 32e6
+               Tcy = 2.0 / Fosc
+               period = 1.0 / freq
+               prescaler = 1
+
+               # find needed prescaler
+               for i in range(4):
+                       prescaler = lPrescaler[i]
+                       PRy = period * 1.0 / (Tcy * prescaler)
+                       PRy = int(PRy - 1)
+                       OCR = int(PRy * duty_cycle)
+
+                       if PRy < (2 ** 16 - 1):
+                               break # valid value for PRy, keep values
+
+               cmd = struct.pack(">BBHH", 0b00010010, prescaler, duty_cycle, period)
+               ret = self.command(cmd, 1)
+               if ord(ret) != 0x1:
+                       raise Exception()
+
        def spi_command(self, cmd):
                ret = self.command(cmd, 1)
                if ord(ret) != 0x1: