My next step was to modify my software so that it would work with the hub.\u00a0 In order to read a sensor, the software would need to know the switches to enable and disable for each sensor, and would need to enable those switches prior to reading the sensor.<\/p>\n
My first thought was to include that information in the configuration file.\u00a0 However this approach would be inflexible, and would not permit multiple hubs as I was only planned to include the information for one switch.<\/p>\n
My next idea was to search the network, locate the switch, and map out the path to each sensor.\u00a0 I got that working, but it still limited me to one switch as I was not searching each path for any additional switches.<\/p>\n
Further research revealed that there is a NetworkMonitor class included in the 1-Wire API that periodically traverses the 1-Wire net and sends a message whenever a a sensor appears or disappears on the network.\u00a0 It uses the Observer design pattern, where the application wanting to receive notifications provides a class instance with the callback methods to the monitor.\u00a0 The information in the callback includes the full path to the sensor through multiple switches if any.\u00a0 This sounded like exactly what I wanted.\u00a0 Support for multiple switches and the ability to dynamically update whenever a sensor was added, removed, or even moved from one port to another.<\/p>\n
Got it working fine in a stand alone program that just monitored the network.\u00a0 When I integrated the network monitor into my program the behavior was different.\u00a0 Every time it traversed the network it showed all the sensors as new.\u00a0 Then it would throw an exception after a few minutes and stop.\u00a0 Some kind of interaction between my code to read the bus and the network monitor.\u00a0 So I moved on to the approach I used as my final solution (for now).\u00a0 This was still my favorite approach, as it permits the network to be dynamic, adapting to sensors coming and going on the bus.\u00a0 I intend to revisit the idea sometime down the road.<\/p>\n
For my next attempt, at program start up I manually traversed the entire network, including any nested switches using a breadth first search algorithm.\u00a0 I created an OWPath object (a class provided in the 1-Wire API) for each sensor found on the net so that the path could be opened and closed when reading the sensor.\u00a0 It doesn’t dynamically adapt to sensors moving or coming and going while the application is running, but it works well for building a static map of the network.\u00a0 I will have to restart the application if the sensors change or move in order to build a new map.\u00a0 I also can log any sensors found on the bus but not in my configuration file, or sensors in the configuration file not found on the bus.\u00a0 I may come back to the NetworkMonitor approach again, but I’m satisfied for now.<\/p>\n
For anybody interested, here’s my code for traversing the 1-Wire network.\u00a0 There are a few things that are specific to my application, but the logic is hopefully clear enough to adapt.\u00a0 Sorry, but the formatting got a bit munged. <\/code><\/p>\n","protected":false},"excerpt":{"rendered":" My next step was to modify my software so that it would work with the hub.\u00a0 In order to read a sensor, the software would need to know the switches to enable and disable for each sensor, and would need … Continue reading
\n<\/p>\n\u00a0\u00a0\u00a0\r\n private Hashtable<String, OWPath> walkNet(DSPortAdapter adapter)\r\n\u00a0\u00a0\u00a0 {\r\n\u00a0\u00a0 \u00a0 \/\/ vector for holding a list of paths to be searched\r\n\u00a0\u00a0 \u00a0 Vector<OWPath> pathsToSearch = new Vector<OWPath>();\r\n\u00a0\u00a0 \u00a0 boolean searchResult = false;\r\n\r\n\u00a0\u00a0 \u00a0 \/\/ hash table for holding the OWPath objects for each\r\n \/\/ device container.\r\n\u00a0\u00a0 \u00a0 Hashtable<String, OWPath> devicePathHash =\r\n new Hashtable<String, OWPath>();\r\n\r\n\u00a0\u00a0 \u00a0 try\r\n\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ seed list with main branch\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 pathsToSearch.addElement(new OWPath(adapter));\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ acquire the adapter\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.beginExclusive(true);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ setup the search\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.setSearchAllDevices();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.targetAllFamilies();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.setSpeed(DSPortAdapter.SPEED_REGULAR);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ walk path and get all devices on branch.\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ if any switches are found, add them to the list\r\n \/\/ of paths to search\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ search through all of the paths\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 for (int i = 0; i < pathsToSearch.size(); i++)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ set searches to not use reset\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 adapter.setNoResetSearch();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ get the next path to search and open it\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 OWPath path = (OWPath)pathsToSearch.elementAt(i);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 try\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ try to open the current path\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 path.open();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 catch(Exception e)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ if opening the path failed, log an error and\r\n \/\/ continue on to the next path\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 ErrorLog.logError(\"walkNet(): Error opening path \"\r\n + path.toString());\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 continue;\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ get the devices on the currently open path\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 searchResult = adapter.findFirstDevice();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ loop while devices found\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 while (searchResult)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ get the 1-Wire address\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 String address = adapter.getAddressAsString();\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ check if the device already exists in the hash\r\n \/\/ table of addresses\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 if (!devicePathHash.containsKey(address))\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 OneWireContainer owc =\r\n adapter.getDeviceContainer(address);\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ check to see if it's a switch.\u00a0 If so, add\r\n \/\/ it to the paths to be searched\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/\u00a0\u00a0 \u00a0if we haven't already searched it\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 if (owc instanceof SwitchContainer)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 SwitchContainer sc = (SwitchContainer)owc;\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 byte[] state = sc.readDevice();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 for (int j = 0;\r\n j < sc.getNumberChannels(state); j++)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 OWPath tmp = new OWPath(adapter, path);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 tmp.add(owc, j);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 if (!pathsToSearch.contains(tmp))\r\n {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 pathsToSearch.addElement(tmp);\r\n }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ save off the address and path\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 synchronized(devicePathHash)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 devicePathHash.put(address, path);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ check if the existing device moved\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 else if (!path.equals((OWPath)\r\n devicePathHash.get(address)))\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 \/\/ if it has moved, add the new\r\n \/\/ address\/path pair\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 synchronized(devicePathHash)\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 devicePathHash.put(address, path);\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ find the next device on this branch\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 path.open();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 searchResult = adapter.findNextDevice();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0 path.close();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 \/\/ clean up after ourselves\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.setSearchAllDevices();\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 adapter.endExclusive();\r\n\u00a0\u00a0 \u00a0 }\r\n\u00a0\u00a0 \u00a0 catch (OneWireException e)\r\n\u00a0\u00a0 \u00a0 {\r\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 ErrorLog.logError(\"Error Serching the 1-Wire Bus\");\r\n\u00a0\u00a0 \u00a0 }\r\n\r\n\u00a0\u00a0 \u00a0 return devicePathHash;\r\n\r\n\u00a0\u00a0\u00a0 }<\/pre>\n