suservo: add clip flags (#992)

artiq/coredevice/suservo.py

@@ -109,8 +109,10 @@ class SUServo:
         """Get current SU Servo status.
 
         This method does not advance the timeline but consumes all slack.
+        This method returns and clears the clip indicator for all channels.
 
-        :return: Status. Bit 0: enabled, bit 1: done
+        :return: Status. Bit 0: enabled, bit 1: done,
+          bits 8-15: channel clip indicators.
         """
         return self.read(CONFIG_ADDR)
 

artiq/examples/kasli_suservo/repository/suservo.py

@@ -29,7 +29,8 @@ class SUServo(EnvExperiment):
         # DDS attenuator
         self.suservo0.cpld0.set_att_mu(0, 64)
         delay(1*us)
-        assert self.suservo0.get_status() == 2
+        # Servo is done
+        assert self.suservo0.get_status() & 0xff == 2
         delay(10*us)
 
         # set up profile 0 on channel 0
@@ -51,16 +52,19 @@ class SUServo(EnvExperiment):
         delay(10*ms)
 
         # check servo status
-        assert self.suservo0.get_status() == 1
+        assert self.suservo0.get_status() & 0xff == 1
         delay(10*us)
 
         # reach back ADC data
-        print(self.suservo0.get_adc_mu(0))
-        delay(10*ms)
+        assert self.suservo0.get_adc_mu(0) == 0
+        delay(10*us)
 
         # read out IIR data
-        print(self.suservo0_ch0.get_y_mu(0))
-        delay(10*ms)
+        assert self.suservo0_ch0.get_y_mu(0) == 0x1ffff
+        delay(10*us)
+
+        assert self.suservo0.get_status() & 0xff00 == 0x0100
+        delay(10*us)
 
         # repeatedly clear the IIR state/integrator
         # with the ADC yielding 0's and given the profile configuration,
@@ -69,6 +73,10 @@ class SUServo(EnvExperiment):
         while True:
             self.suservo0_ch0.set(1, 0, 0)
             delay(1*us)
+            assert self.suservo0.get_status() & 0xff00 == 0x0100
+            delay(10*us)
+            assert self.suservo0.get_status() & 0xff00 == 0x0000
+            delay(10*us)
             self.suservo0_ch0.set_y_mu(0, 0)
             delay(1*us)
             self.suservo0_ch0.set(1, 1, 0)

artiq/gateware/rtio/phy/servo.py

@@ -58,9 +58,11 @@ class RTServoMem(Module):
 
         config = Signal(w.coeff, reset=0)
         status = Signal(w.coeff)
+        pad = Signal(6)
         self.comb += [
                 Cat(servo.start).eq(config),
-                status.eq(Cat(servo.start, servo.done))
+                status.eq(Cat(servo.start, servo.done, pad,
+                    [_.clip for _ in servo.iir.ctrl]))
         ]
 
         assert len(self.rtlink.o.address) == (
@@ -108,6 +110,9 @@ class RTServoMem(Module):
         self.sync.rio_phy += [
                 If(self.rtlink.o.stb & we & state_sel & config_sel,
                     config.eq(self.rtlink.o.data)
+                ),
+                If(read & read_config & read_state,
+                    [_.clip.eq(0) for _ in servo.iir.ctrl]
                 )
         ]
         self.comb += [

artiq/gateware/suservo/iir.py

@@ -238,6 +238,7 @@ class IIR(Module):
             ("profile", w.profile),
             ("en_out", 1),
             ("en_iir", 1),
+            ("clip", 1),
             ("stb", 1)])
             for i in range(1 << w.channel)]
         # only update during ~loading
@@ -266,6 +267,7 @@ class IIR(Module):
         profiles = Array([ch.profile for ch in self.ctrl])
         en_outs = Array([ch.en_out for ch in self.ctrl])
         en_iirs = Array([ch.en_iir for ch in self.ctrl])
+        clips = Array([ch.clip for ch in self.ctrl])
 
         # state counter
         state = Signal(w.channel + 2)
@@ -443,8 +445,10 @@ class IIR(Module):
                         en_out.eq(en_outs[channel[0]]),
                         en_iir.eq(en_iirs[channel[0]]),
                         If(stage[1],
-                            ddss[channel[1]][:w.word].eq(
-                                m_coeff.dat_r),
+                            ddss[channel[1]][:w.word].eq(m_coeff.dat_r)
+                        ),
+                        If(stage[2] & en[1] & dsp.clip,
+                            clips[channel[2]].eq(1)
                         )
                     ],
                     1: [