Add a glasgow voltage command-line verb.

Also fix some glitches related to alerts.

firmware/adc.c

@@ -140,12 +140,10 @@ bool iobuf_set_alert(uint8_t mask,
 
       if(!adc_reg_write(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
         return false;
-
-      return true;
     }
   }
 
-  return false;
+  return true;
 }
 
 bool iobuf_get_alert(uint8_t selector,
@@ -160,7 +158,7 @@ bool iobuf_get_alert(uint8_t selector,
       if(!adc_reg_read(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
         return false;
 
-      if(!(control_byte & ADC081_BIT_ALERT_PIN_EN)) {
+      if(control_byte == 0) {
         *low_millivolts = 0;
         *high_millivolts = MAX_VOLTAGE;
         return true;
@@ -193,22 +191,24 @@ bool iobuf_poll_alert(__xdata uint8_t *mask, bool clear) {
       return false;
 
     if(status_byte) {
+      __pdata uint8_t control_byte = 0;
       *mask |= buffer->selector;
 
+      if(!adc_reg_read(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
+        return false;
+
       if(clear) {
-        // Actually clear alert
+        // Clear actual alert and re-arm the alert pin
         if(!adc_reg_write(buffer->address, ADC081_REG_ALERT_STATUS, &status_byte, 1))
           return false;
+        control_byte |=  ADC081_BIT_ALERT_PIN_EN;
       } else {
-        // Only clear alert pin status
-        __pdata uint8_t control_byte = 0;
-        if(!adc_reg_read(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
-          return false;
-
+        // Only disarm the alert pin (so that alerts from other ADCs can be detected)
         control_byte &= ~ADC081_BIT_ALERT_PIN_EN;
-        if(!adc_reg_write(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
-          return false;
       }
+
+      if(!adc_reg_write(buffer->address, ADC081_REG_CONFIGURATION, &control_byte, 1))
+        return false;
     }
   }
 

software/glasgow/cli.py

@@ -1,5 +1,6 @@
 import os
 import argparse
+import time
 
 from fx2 import FX2DeviceError
 
@@ -13,6 +14,21 @@ def get_argparser():
     subparsers = parser.add_subparsers(dest="action", metavar="COMMAND")
     subparsers.required = True
 
+    p_voltage = subparsers.add_parser(
+        "voltage", help="query or set I/O port voltage")
+    p_voltage.add_argument(
+        "ports", metavar="PORTS", type=str, nargs='?', default="AB",
+        help="I/O port set (one or more of: A B, default: all)")
+    p_voltage.add_argument(
+        "voltage", metavar="VOLTS", type=float, nargs='?', default=None,
+        help="I/O port voltage (range: 1.8-5.0)")
+    p_voltage.add_argument(
+        "--tolerance", metavar="PCT", type=float, default=10.0,
+        help="raise alert if measured voltage deviates by more than ±PCT%%")
+    p_voltage.add_argument(
+        "--no-alert", dest="set_alert", default=True, action="store_false",
+        help="do not raise an alert if Vsense is out of range of Vio")
+
     p_download = subparsers.add_parser(
         "download", help="volatile download bitstream to FPGA")
     p_download.add_argument(
@@ -40,18 +56,45 @@ def main():
     try:
         firmware_file = os.path.join(os.path.dirname(__file__), "glasgow.ihex")
         device = GlasgowDevice(firmware_file)
-    except (FX2DeviceError, GlasgowDeviceError) as e:
-        raise SystemExit(e)
 
-    if args.action == "download":
-        device.download_bitstream(args.bitstream.read())
-    if args.action == "test":
-        if args.mode == "toggle-io":
-            device.download_bitstream(TestToggleIO().get_bitstream(debug=True))
-            device.set_voltage("AB", 3.3)
-        if args.mode == "expose-i2c":
-            device.download_bitstream(TestExposeI2C().get_bitstream(debug=True))
-            device.set_voltage("A", 3.3)
+        if args.action == "voltage":
+            if args.voltage is not None:
+                device.reset_alert(args.ports)
+                device.poll_alert() # clear any remaining alerts
+                device.set_voltage(args.ports, args.voltage)
+                if args.set_alert and args.voltage != 0.0:
+                    time.sleep(0.050) # let the output capacitor discharge a bit
+                    tolerance  = args.tolerance / 100
+                    low_volts  = args.voltage * (1 - tolerance)
+                    high_volts = args.voltage * (1 + tolerance)
+                    device.set_alert(args.ports, low_volts, high_volts)
+
+            print("Port\tVio\tVsense\tRange")
+            alerts = device.poll_alert()
+            for port in args.ports:
+                vio = device.get_voltage(port)
+                vsense = device.measure_voltage(port)
+                alert = device.get_alert(port)
+                if port in alerts:
+                    notice = " (ALERT)"
+                else:
+                    notice = ""
+                print("{}\t{:.2}\t{:.3}\t{:.2}-{:.2}{}"
+                      .format(port, vio, vsense, alert[0], alert[1], notice))
+
+        if args.action == "download":
+            device.download_bitstream(args.bitstream.read())
+
+        if args.action == "test":
+            if args.mode == "toggle-io":
+                device.download_bitstream(TestToggleIO().get_bitstream(debug=True))
+                device.set_voltage("AB", 3.3)
+            if args.mode == "expose-i2c":
+                device.download_bitstream(TestExposeI2C().get_bitstream(debug=True))
+                device.set_voltage("A", 3.3)
+
+    except FX2DeviceError as e:
+        raise SystemExit(e)
 
 
 if __name__ == "__main__":

software/glasgow/device.py

@@ -166,7 +166,7 @@ def measure_voltage(self, spec):
         except usb1.USBErrorPipe:
             raise GlasgowDeviceError("Cannot measure port {} sense voltage".format(spec))
 
-    def set_alert(self, spec, low_volts=0.0, high_volts=5.5):
+    def set_alert(self, spec, low_volts, high_volts):
         low_millivolts  = round(low_volts * 1000)
         high_millivolts = round(high_volts * 1000)
         self.control_write(usb1.REQUEST_TYPE_VENDOR, REQ_ALERT_VOLT,
@@ -178,6 +178,9 @@ def set_alert(self, spec, low_volts=0.0, high_volts=5.5):
                                      .format(spec or "(none)",
                                              float(low_volts), float(high_volts)))
 
+    def reset_alert(self, spec):
+        self.set_alert(spec, 0.0, 5.5)
+
     def get_alert(self, spec):
         try:
             low_millivolts, high_millivolts = struct.unpack("<HH",