Introduced two new methods:

powerOff():
This will put the enc28j60 module into the sleep mode.

powerOn():
This will wake up the enc28j60 module back from sleep mode.

Usage:

void loop()
{
  Ethernet.maintain();
  [...]
  Ethernet.getNetwork().powerOff();
}

Author: virusbrain

UIPEthernet.cpp

@@ -410,6 +410,12 @@ UIPEthernetClass::upper_layer_chksum(uint8_t proto)
   return (sum == 0) ? 0xffff : htons(sum);
 }
 
+Enc28J60Network 
+UIPEthernetClass::getNetwork()
+{
+  return network;
+}
+
 uint16_t
 uip_ipchksum(void)
 {

UIPEthernet.h

@@ -81,6 +81,8 @@ class UIPEthernetClass
   IPAddress gatewayIP();
   IPAddress dnsServerIP();
 
+  Enc28J60Network getNetwork();
+
 private:
   IPAddress _dnsServerAddress;
   DhcpClass* _dhcp;

utility/Enc28J60Network.cpp

@@ -552,3 +552,22 @@ Enc28J60Network::chksum(uint16_t sum, memhandle handle, memaddress pos, uint16_t
   /* Return sum in host byte order. */
   return sum;
 }
+
+void
+Enc28J60Network::powerOff()
+{
+  writeOp(ENC28J60_BIT_FIELD_CLR, ECON1, ECON1_RXEN);
+  delay(50);
+  writeOp(ENC28J60_BIT_FIELD_SET, ECON2, ECON2_VRPS);
+  delay(50);
+  writeOp(ENC28J60_BIT_FIELD_SET, ECON2, ECON2_PWRSV);
+}
+
+void
+Enc28J60Network::powerOn()
+{
+  writeOp(ENC28J60_BIT_FIELD_CLR, ECON2, ECON2_PWRSV);
+  delay(50);
+  writeOp(ENC28J60_BIT_FIELD_SET, ECON1, ECON1_RXEN);
+  delay(50);
+}

utility/Enc28J60Network.h

@@ -81,6 +81,8 @@ class Enc28J60Network : public MemoryPool
   uint16_t writePacket(memhandle handle, memaddress position, uint8_t* buffer, uint16_t len);
   void copyPacket(memhandle dest, memaddress dest_pos, memhandle src, memaddress src_pos, uint16_t len);
   uint16_t chksum(uint16_t sum, memhandle handle, memaddress pos, uint16_t len);
+  void powerOn();
+  void powerOff();
 };
 
 #endif /* ENC28J60NETWORK_H_ */