add start method fix pinRead for port B

lib/mcp23008-17.js

@@ -36,9 +36,34 @@ class MCP23008 extends Device {
     return _u.pSeries(jobs)
   }
 
+  start() {
+    let starts = []
+    for (let port in this.ports) {
+      if (this.inter(port)) {
+        starts.push(
+          this.read(portReg(0x08, port))
+          .then(_u.pDelay(100)) // give enough time for mcp to reset its interupt
+          .then(() => {
+            return this.inter(port).start()
+              .then(() => {
+                return Promise.resolve(`interrupt port ${port} started`)
+              })
+          })
+        )
+      }
+    }
+    return Promise.all(starts)
+  }
+
   pin(id) { return this.ports.A.pin(id) } // get a reference to a particular pin's object
+
   pid(address) { return this.ports.A.pid(address) } // return pin id for a given address on a port
 
+  portByPin(id) {
+    if (this.ports.A.pin(id)) { return 'A' }
+    return false
+  }
+
   inter(port = 'A') {
     return this.ports[port].interrupt
   }
@@ -95,11 +120,9 @@ class MCP23008 extends Device {
           if (!gpio) {
             reject('no pin found for given id')
           }
-          if (gpio.port === 'B') {
-            reg = reg + 0x10
-          }
-          // console.log('port - reg', gpio.port, reg)
-          return mcpdev.read(reg).then(resp => {
+          console.log('id of fired pin', id)
+          console.log('port of fired pin', mcpdev.portByPin(id))
+          return mcpdev.read(portReg(reg, mcpdev.portByPin(id))).then(resp => {
               resp = _u.byteFormat(resp, { in: 'DEC',
                 out: 'ARY'
               })
@@ -168,9 +191,20 @@ class MCP23017 extends MCP23008 {
     return this.ports[port].pid(address)
   }
 
+  portByPin(id) {
+    console.log('pin id in portbypin', id)
+    if (this.ports.A.pin(id)) { return 'A' }
+    if (this.ports.B.pin(id)) { return 'B' }
+    return false
+  }
+
 } // end MCP23017 Class
 module.exports.MCP23017 = MCP23017
 
+function portReg(reg, port) {
+  if (port === 'B') { return reg += 0x10 } else { return reg }
+}
+
 /* ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf
  * or see MCP23017.pdf and MCP 23008.pdf in /docs
  * see table 1.5 and details in sections 1.6.x following