add RP2040

GPIO/RP2040/ring.RP2040.ino

+//
+// ring.RP2040.ino
+//    RP2040 ring oscillator test
+//    connect P1 and P2
+//
+// Neil Gershenfeld 12/26/22
+//
+// This work may be reproduced, modified, distributed,
+// performed, and displayed for any purpose, but must
+// acknowledge this project. Copyright is retained and
+// must be preserved. The work is provided as is; no
+// warranty is provided, and users accept all liability.
+//
+
+void setup() {
+   //
+   // nothing to do in first core
+   //
+   }
+
+void loop() {
+   }
+
+void setup1() {
+   //
+   // use second core to avoid Arduino interrupts
+   //
+   pinMode(2,OUTPUT);
+   }
+
+void loop1() {
+   //
+   // direct port I/O version
+   //    9.17 MHz at 133 MHz clock
+   //
+   uint32_t pin1 = (1 << 1);
+   uint32_t pin2 = (1 << 2);
+   while (1) {
+      if (pin1 & sio_hw->gpio_in)
+         sio_hw->gpio_clr = pin2;
+      else
+         sio_hw->gpio_set = pin2;
+      }
+   //
+   // Arduino version
+   //    584 kHz at 133 MHz clock
+   //
+   /*
+   while (1) {
+      if (digitalRead(1))
+         digitalWrite(2,LOW);
+      else
+         digitalWrite(2,HIGH);
+      }
+   */
+   }

GPIO/RP2040/ring.RP2040.py

+#
+# ring.RP2040.py
+#    RP2040 ring oscillator test
+#    connect P1 and P2
+#
+# Neil Gershenfeld 12/25/22
+#
+# This work may be reproduced, modified, distributed,
+# performed, and displayed for any purpose, but must
+# acknowledge this project. Copyright is retained and
+# must be preserved. The work is provided as is; no
+# warranty is provided, and users accept all liability.
+#
+from machine import Pin
+machine.freq(133000000)
+p1 = Pin(1,Pin.IN)
+p2 = Pin(2,Pin.OUT)
+while (True):
+    p2.value(1-p1.value())