Expose ability to overclock RP2040

Author: MichaelBell

src/ttboard/demoboard.py

@@ -321,7 +321,7 @@ def _clock_pwm_deinit(self):
         self._clock_pwm.deinit()
         self._clock_pwm = None 
 
-    def clock_project_PWM(self, freqHz:int, duty_u16:int=(0xffff/2), quiet:bool=False):
+    def clock_project_PWM(self, freqHz:int, duty_u16:int=(0xffff/2), quiet:bool=False, max_rp2040_freq:int=133_000_000):
         '''
             Start an automatic clock for the selected project (using
             PWM).
@@ -353,8 +353,10 @@ def clock_project_PWM(self, freqHz:int, duty_u16:int=(0xffff/2), quiet:bool=Fals
             if self._clock_pio is not None:
                 self._clock_pio.stop()
             try:
-                rp2040_sys_clock = self._get_best_rp2040_freq(freqHz)
-                platform.set_RP_system_clock(rp2040_sys_clock)
+                rp2040_sys_clock = self._get_best_rp2040_freq(freqHz, max_rp2040_freq)
+                if rp2040_sys_clock != platform.get_RP_system_clock():
+                    log.info(f'Setting RP2040 system clock to {sys_clk_hz}Hz')
+                    platform.set_RP_system_clock(rp2040_sys_clock)
                 self._clock_pwm = self.pins.rp_projclk.pwm(freqHz, duty_u16)
             except  Exception as e:
                 log.error(f"Could not set project clock PWM: {e}")