Revision 75:ce6e12067d0c, committed 2014-05-16

Comitter:

mazgch

Date:

Fri May 16 14:13:00 2014 +0000

Parent:

74:208e3e32d263

Child:

76:f7c3dd568dae

Commit message:

minor tweaks

Changed in this revision

--- a/GPS.cpp	Thu May 15 22:20:42 2014 +0000
+++ b/GPS.cpp	Fri May 16 14:13:00 2014 +0000
@@ -258,7 +258,7 @@
 #endif
 }
 
-bool GPSSerial::init(void)
+bool GPSSerial::init(PinName pn)
 {
     // send a byte to wakup the device again
     putc(0);
@@ -301,12 +301,14 @@
 #endif
 }
 
-bool GPSI2C::init(void)
+bool GPSI2C::init(PinName pn)
 {
-    DigitalOut pin(GPSINT, 0);
-    wait_us(1);
-    pin = 1;
-    RELAX_MS(100);
+    if (pn != NC) {
+        DigitalOut pin(pn, 0);
+        wait_us(1);
+        pin = 1;
+        RELAX_MS(100);
+    }
     return !I2C::write(_i2cAdr,&REGSTREAM,sizeof(REGSTREAM));
 }
 

--- a/GPS.h	Thu May 15 22:20:42 2014 +0000
+++ b/GPS.h	Fri May 16 14:13:00 2014 +0000
@@ -5,9 +5,9 @@
 #include "SerialPipe.h"
 
 #ifdef TARGET_UBLOX_C027
- #define _IF(onboard, shield) onboard
+ #define GPS_IF(onboard, shield) onboard
 #else
- #define _IF(onboard, shield) shield
+ #define GPS_IF(onboard, shield) shield
 #endif
 
 /** basic gps parser class 
@@ -21,7 +21,7 @@
    
     /** Power on / Wake up the gps 
     */
-    virtual bool init(void) = 0;
+    virtual bool init(PinName pn) = 0;
     
     enum { 
         // getLine Responses
@@ -178,13 +178,13 @@
         \param rxSize the size of the serial rx buffer
         \param txSize the size of the serial tx buffer
     */
-    GPSSerial(PinName tx    _IF( = GPSTXD, /* = D8 */), // resistor on shield not populated 
-              PinName rx    _IF( = GPSRXD, /* = D9 */), // resistor on shield not populated 
-              int baudrate  _IF( = GPSBAUD, = 9600 ),
+    GPSSerial(PinName tx    GPS_IF( = GPSTXD, /* = D8 */), // resistor on shield not populated 
+              PinName rx    GPS_IF( = GPSRXD, /* = D9 */), // resistor on shield not populated 
+              int baudrate  GPS_IF( = GPSBAUD, = 9600 ),
               int rxSize    = 256 , 
               int txSize    = 128 );
               
-    virtual bool init(void);
+    virtual bool init(PinName pn = NC);
     
     /** Get a line from the physical interface. 
         \param buf the buffer to store it
@@ -215,15 +215,15 @@
         \param adr the I2C address of the GPS set to (66<<1)
         \param rxSize the size of the serial rx buffer
     */
-    GPSI2C(PinName sda          _IF( = GPSSDA, = D14 ), 
-           PinName scl          _IF( = GPSSCL, = D15 ),
-           unsigned char i2cAdr _IF( = GPSADR, = (66<<1) ), 
+    GPSI2C(PinName sda          GPS_IF( = GPSSDA, = D14 ), 
+           PinName scl          GPS_IF( = GPSSCL, = D15 ),
+           unsigned char i2cAdr GPS_IF( = GPSADR, = (66<<1) ), 
            int rxSize           = 256 );
     
     /** helper function to probe the i2c device
         \return true if successfully detected the gps. 
     */ 
-    virtual bool init(void);
+    virtual bool init(PinName pn = GPS_IF( GPSINT, NC /* D7 resistor R67 on shield not mounted */));
     
     /** Get a line from the physical interface. 
         \param buf the buffer to store it

--- a/MDM.cpp	Thu May 15 22:20:42 2014 +0000
+++ b/MDM.cpp	Fri May 16 14:13:00 2014 +0000
@@ -11,27 +11,40 @@
 #define MAX_SIZE        128   //!< max expected messages
 //! test if it is a socket
 #define ISSOCKET(s)     (((s) >= 0) && ((s) < (sizeof(_sockets)/sizeof(*_sockets))))
-
+//! check for timeout
+#define TIMEOUT(t, ms)  ((ms != TIMEOUT_BLOCKING) && (ms < t.read_ms())) 
 
 #ifdef MDM_DEBUG
 void dumpAtCmd(const char* buf, int len)
 {
-    printf(" %3d \"", len);
+    ::printf(" %3d \"", len);
     while (len --) {
         char ch = *buf++;
-        if      (ch == '\r') puts("\\r");
-        else if (ch == '\n') puts("\\n");
-        else if (ch >= 0x20) putchar(ch);
-        else                 printf("\\x%02x", ch);
+        if ((ch > 0x1F) && (ch != 0x7F)) { // is printable
+            if      (ch == '%')  ::printf("%%");
+            else if (ch == '"')  ::printf("\\\"");
+            else if (ch == '\\') ::printf("\\\\");
+            else putchar(ch);
+        } else {
+            if      (ch == '\a') ::printf("\\a"); // BEL (0x07)
+            else if (ch == '\b') ::printf("\\b"); // Backspace (0x08)
+            else if (ch == '\t') ::printf("\\t"); // Horizontal Tab (0x09)
+            else if (ch == '\n') ::printf("\\n"); // Linefeed (0x0A)
+            else if (ch == '\v') ::printf("\\v"); // Vertical Tab (0x0B)
+            else if (ch == '\f') ::printf("\\f"); // Formfeed (0x0C)
+            else if (ch == '\r') ::printf("\\r"); // Carriage Return (0x0D)
+            else                 ::printf("\\x%02x", ch);
+        }
     }
-    puts("\"\r\n");
+    ::printf("\"\r\n");
 }
  
- #define INFO  (_debugLevel >= 1) ? : printf
- #define TRACE (_debugLevel >= 2) ? : printf
+ #define ERROR(fmt) (_debugLevel < 0) ? : ::printf(RED(fmt))
+ #define INFO(fmt)  (_debugLevel < 1) ? : ::printf(GRE(fmt))
+ #define TRACE(...) (_debugLevel < 2) ? : ::printf(__VA_ARGS__)
  
  #if 1 // colored terminal output using ANSI escape sequences
-  #define COL(c,t) "\33[" c t "\33[" "39m"
+  #define COL(c,t) "\033[" c t "\033[" "39m"
  #else
   #define COL(c,t) t
  #endif
@@ -46,6 +59,7 @@
  
 #else
  
+ #define ERROR(...) (void)0 // no tracing
  #define INFO(...)  (void)0 // no tracing
  #define TRACE(...) (void)0 // no tracing
 
@@ -80,7 +94,7 @@
 {
 #ifdef MDM_DEBUG
     if (_debugLevel >= 3) {
-        printf("%10.3f AT send    ", _debugTime.read_ms()*0.001);
+        ::printf("%10.3f AT send    ", _debugTime.read_ms()*0.001);
         dumpAtCmd(buf,len);
     }
 #endif
@@ -117,16 +131,13 @@
                             (type == TYPE_PLUS)   ? CYA(" + ") : 
                             (type == TYPE_PROMPT) ? BLU(" > ") : 
                                                         "..."  ;
-            printf("%10.3f AT read %s", _debugTime.read_ms()*0.001, s);
+            ::printf("%10.3f AT read %s", _debugTime.read_ms()*0.001, s);
             dumpAtCmd(buf, len);
         }
 #endif        
         if ((ret != WAIT) && (ret != NOT_FOUND))
         {
             int type = TYPE(ret);
-            if (type == TYPE_OK)        return RESP_OK;
-            if (type == TYPE_ERROR)     return RESP_ERROR;
-            if (type == TYPE_PROMPT)    return RESP_PROMPT;
             // handle unsolicited commands here
             if (type == TYPE_PLUS) {
                 const char* cmd = buf+3;
@@ -208,14 +219,14 @@
                 if (WAIT != ret)
                     return ret; 
             }
+            if (type == TYPE_OK)        return RESP_OK;
+            if (type == TYPE_ERROR)     return RESP_ERROR;
+            if (type == TYPE_PROMPT)    return RESP_PROMPT;
         }
         // relax a bit
         RELAX_MS(10); 
     }
-    while ((timeout_ms == TIMEOUT_BLOCKING) || 
-           (timer.read_ms() < timeout_ms));
-    timer.stop();
-    timer.reset();
+    while (!TIMEOUT(timer, timeout_ms));
     return WAIT;
 }
 
@@ -244,28 +255,17 @@
             const char* apn, const char* username, const char* password,
             PinName pn)
 {
-    DevStatus devStatus = {};
-    bool mdmOk = init(simpin, &devStatus, pn);  
+    bool ok = init(simpin, NULL, pn);  
 #ifdef MDM_DEBUG
-    if (_debugLevel >= 1) dumpDevStatus(&devStatus);
+    if (_debugLevel >= 1) dumpDevStatus(&_dev);
 #endif
-    if (!mdmOk)
+    if (!ok)
         return false;
-    // wait until we are connected
-    int i = 180;
-    NetStatus netStatus = {};
-    INFO("Modem::register\r\n");
-    while (!checkNetStatus(&netStatus))
-    {
-        if ((netStatus.reg == REG_DENIED) || (i == 0))
-            break;;
-        i --;
-        RELAX_MS(1000);
-    }
+    ok = registerNet();
 #ifdef MDM_DEBUG
-    if (_debugLevel >= 1) dumpNetStatus(&netStatus);
+    if (_debugLevel >= 1) dumpNetStatus(&_net);
 #endif
-    if ((netStatus.reg == REG_DENIED) || (i == 0))
+    if (!ok)
         return false;
     IP ip = join(apn,username,password);
 #ifdef MDM_DEBUG
@@ -292,9 +292,12 @@
             if(RESP_OK == waitFinalResp(NULL,NULL,500))
                 break;
         }
-        if (i < 0)
+        if (i < 0) {
+            ERROR("No Reply from Modem");
             return false;
+        }
     }
+    
     INFO("Modem::init\r\n");
     // echo off
     sendFormated("AT E0\r\n");
@@ -363,9 +366,12 @@
             if ((RESP_OK != ret) && (RESP_ERROR != ret))
                 return false;
             // Enter PIN if needed
-            if (_dev.sim == SIM_PIN) {
+            if (_dev.sim == SIM_MISSING) {
+                ERROR("SIM not inserted\r\n");
+                return false;
+            } else if (_dev.sim == SIM_PIN) {
                 if (!simpin) {
-                    INFO("SIM PIN not available\r\n");
+                    ERROR("SIM PIN not available\r\n");
                     return false;
                 }
                 sendFormated("AT+CPIN=%s\r\n", simpin);
@@ -398,12 +404,6 @@
         sendFormated("AT+CGSN\r\n");
         if (RESP_OK != waitFinalResp(_cbString, _dev.imei))
             return false;
-#if 0
-        // Configure New message indication
-        sendFormated("AT+CNMI=2,1,0,0,0\r\n");
-        if (RESP_OK != waitFinalResp())
-            return false;
-#endif
         // enable power saving
         if (_dev.lpm != LPM_DISABLED) {
              // enable power saving (requires flow control, cts at least)
@@ -418,7 +418,7 @@
     if (RESP_OK != waitFinalResp())
         return false;
     // setup new message indication
-    sendFormated("AT+CNMI=1,1\r\n");
+    sendFormated("AT+CNMI=2,1\r\n");
     if (RESP_OK != waitFinalResp())
         return false;
     // Request IMSI (International Mobile Subscriber Identification)
@@ -462,10 +462,14 @@
 
 int MDMParser::_cbCPIN(int type, const char* buf, int len, Sim* sim)
 {
-    if ((type == TYPE_PLUS) && sim){
-        char s[16];
-        if (sscanf(buf, "\r\n+CPIN: %[^\r]\r<n", s) >= 1) {
-            *sim = (strcmp("READY", s) == 0) ? SIM_READY : SIM_PIN;
+    if (sim) {
+        if (type == TYPE_PLUS){
+            char s[16];
+            if (sscanf(buf, "\r\n+CPIN: %[^\r]\r\n", s) >= 1)
+                *sim = (0 == strcmp("READY", s)) ? SIM_READY : SIM_PIN;
+        } else if (type == TYPE_ERROR) {
+            if (strstr(buf, "+CME ERROR: SIM not inserted"))
+                *sim = SIM_MISSING;
         }
     }
     return WAIT;
@@ -480,53 +484,69 @@
     return WAIT;
 }
 
+bool MDMParser::registerNet(NetStatus* status /*= NULL*/, int timeout_ms /*= 180000*/) 
+{
+    Timer timer;
+    timer.start();
+    INFO("Modem::register\r\n");
+    while (!checkNetStatus(status) && !TIMEOUT(timer, timeout_ms))
+        RELAX_MS(1000);
+    if (_net.reg == REG_DENIED)
+        ERROR("Network Registration Denied\r\n");
+    return (_net.reg == REG_ROAMING) || (_net.reg == REG_HOME);
+}
+
 bool MDMParser::checkNetStatus(NetStatus* status /*= NULL*/)
 {
+    memset(&_net, 0, sizeof(_net));
+    _net.lac = 0xFFFF;
+    _net.ci = 0xFFFFFFFF;
     // check registration
     sendFormated("AT+CREG?\r\n");
     if (RESP_OK != waitFinalResp())
         return false;
-    if ((_net.reg != REG_ROAMING) && (_net.reg != REG_HOME))
-        return false;
-    // check modem specific status messages 
-    if (_dev.dev == DEV_LISA_C200) {
-        sendFormated("AT+CSS?\r\n");
-        if (RESP_OK != waitFinalResp())
-            return false;
-        // get the Telephone number
-        sendFormated("AT$MDN?\r\n");
-        if (RESP_OK != waitFinalResp(_cbString, _net.num))
-            return false;
-        // check if we have a Mobile Directory Number
-        if (memcmp(_net.num, "0000", 4) == 0)
-            return false;
-        // get the the Network access identifier string
-        char nai[64];
-        sendFormated("AT$QCMIPNAI?\r\n");
-        if (RESP_OK != waitFinalResp(_cbString, nai))
+    if ((_net.reg == REG_ROAMING) || (_net.reg == REG_HOME))
+    {
+        // check modem specific status messages 
+        if (_dev.dev == DEV_LISA_C200) {
+            sendFormated("AT+CSS?\r\n");
+            if (RESP_OK != waitFinalResp())
+                return false;
+            // get the Telephone number
+            sendFormated("AT$MDN?\r\n");
+            if (RESP_OK != waitFinalResp(_cbString, _net.num))
+                return false;
+            // check if we have a Mobile Directory Number
+            if (!*_net.num || (memcmp(_net.num, "0000", 4) == 0))
+                return false;
+            // get the the Network access identifier string
+            char nai[64];
+            sendFormated("AT$QCMIPNAI?\r\n");
+            if (RESP_OK != waitFinalResp(_cbString, nai))
+                return false;
+        } else {
+            // check GPRS attach status
+            sendFormated("AT+CGATT?\r\n");
+            if (RESP_OK != waitFinalResp(_cbCGATT, &_net.gprs))
+                return false;
+            // check operator selection 
+            sendFormated("AT+COPS?\r\n");
+            if (RESP_OK != waitFinalResp(_cbCOPS, &_net))
+                return false;
+            // Returns the MSISDNs related to this subscriber
+            sendFormated("AT+CNUM\r\n");
+            if (RESP_OK != waitFinalResp(_cbCNUM, _net.num))
+                return false;
+        }  
+        // Returns the signal strength indication
+        sendFormated("AT+CSQ\r\n");
+        if (RESP_OK != waitFinalResp(_cbCSQ, &_net))
             return false;
-    } else {
-        // check GPRS attach status
-        sendFormated("AT+CGATT?\r\n");
-        if (RESP_OK != waitFinalResp(_cbCGATT, &_net.gprs))
-            return false;
-        // check operator selection 
-        sendFormated("AT+COPS?\r\n");
-        if (RESP_OK != waitFinalResp(_cbCOPS, &_net))
-            return false;
-        // Returns the MSISDNs related to this subscriber
-        sendFormated("AT+CNUM\r\n");
-        if (RESP_OK != waitFinalResp(_cbCNUM, _net.num))
-            return false;
-    }  
-    // Returns the signal strength indication
-    sendFormated("AT+CSQ\r\n");
-    if (RESP_OK != waitFinalResp(_cbCSQ, &_net))
-        return false;
+    }
     if (status) {
         memcpy(status, &_net, sizeof(NetStatus));
     }
-    return true;
+    return ((_net.reg == REG_HOME) || (_net.reg == REG_ROAMING) || (_net.reg == REG_DENIED));
 }
 
 int MDMParser::_cbCGATT(int type, const char* buf, int len, Gprs* gprs)
@@ -636,7 +656,7 @@
         // Activate the profile and make connection
         sendFormated("AT+UPSDA=" PROFILE ",3\r\n");
         if (RESP_OK != waitFinalResp(NULL,NULL,150*1000)) {
-            INFO("Your modem APN/password/username may be wrong\r\n");
+            ERROR("Your modem APN/password/username may be wrong\r\n");
             return NOIP;
         }
         //Get local IP address
@@ -900,18 +920,14 @@
             cnt += blk;
             buf += blk;
             _sockets[socket].pending -= blk;
-        } else if ((_sockets[socket].state == SOCK_CONNECTED) && (
-                   (_sockets[socket].timeout_ms == TIMEOUT_BLOCKING) || 
-                   (timer.read_ms() < _sockets[socket].timeout_ms))){
+        } else if ((_sockets[socket].state == SOCK_CONNECTED) && 
+                   !TIMEOUT(timer, _sockets[socket].timeout_ms)) {
             // allow to receive unsolicited commands 
             waitFinalResp(NULL, NULL, 10);
         } else {
             len = 0; // no more data and socket closed or timed-out
         }
     }
-    
-    timer.stop();
-    timer.reset();
     return cnt;
 }
 
@@ -957,13 +973,11 @@
             cnt += blk;
             buf += blk;
             _sockets[socket].pending -= blk;
-        } else if ((_sockets[socket].timeout_ms == TIMEOUT_BLOCKING) || 
-                   (timer.read_ms() < _sockets[socket].timeout_ms)) {
+        } else if (!TIMEOUT(timer, _sockets[socket].timeout_ms)) {
             // allow to receive unsolicited commands 
             waitFinalResp(NULL, NULL, 10);
-        } else {
+        } else
             len = 0; // no more data and socket closed or timed-out
-        }
     }
     timer.stop();
     timer.reset();
@@ -1084,14 +1098,14 @@
 void MDMParser::dumpDevStatus(MDMParser::DevStatus* status, 
             _DPRINT dprint, void* param) 
 {
-    dprint(param, "Modem Device Status:\r\n");
+    dprint(param, "Modem::devStatus\r\n");
     const char* txtDev[] = { "Unknown", "SARA-G350", "LISA-U200", "LISA-C200" };
     if (status->dev < sizeof(txtDev)/sizeof(*txtDev) && (status->dev != MDMParser::DEV_UNKNOWN))
         dprint(param, "  Device:       %s\r\n", txtDev[status->dev]);
     const char* txtLpm[] = { "Disabled", "Enabled", "Active" };
     if (status->lpm < sizeof(txtLpm)/sizeof(*txtLpm))
         dprint(param, "  Power Save:   %s\r\n", txtLpm[status->lpm]);
-    const char* txtSim[] = { "Unknown", "Pin", "Ready" };
+    const char* txtSim[] = { "Unknown", "Missing", "Pin", "Ready" };
     if (status->sim < sizeof(txtSim)/sizeof(*txtSim) && (status->sim != MDMParser::SIM_UNKNOWN))
         dprint(param, "  SIM:          %s\r\n", txtSim[status->sim]);
     if (*status->ccid)  
@@ -1113,7 +1127,7 @@
 void MDMParser::dumpNetStatus(MDMParser::NetStatus *status,
             _DPRINT dprint, void* param)
 {
-    dprint(param, "Modem Network Status:\r\n");
+    dprint(param, "Modem::netStatus\r\n");
     const char* txtReg[] = { "Unknown", "Denied", "None", "Home", "Roaming" };
     if (status->reg < sizeof(txtReg)/sizeof(*txtReg) && (status->reg != MDMParser::REG_UNKNOWN))
         dprint(param, "  Registration:       %s\r\n", txtReg[status->reg]);
@@ -1141,7 +1155,7 @@
             _DPRINT dprint, void* param) 
 {
     if (ip != NOIP)
-        dprint(param, "Modem IP Address: " IPSTR "\r\n", IPNUM(ip));
+        dprint(param, "Modem:IP " IPSTR "\r\n", IPNUM(ip));
 }
     
 // ----------------------------------------------------------------

--- a/MDM.h	Thu May 15 22:20:42 2014 +0000
+++ b/MDM.h	Fri May 16 14:13:00 2014 +0000
@@ -7,9 +7,9 @@
 #include "SerialPipe.h"
 
 #ifdef TARGET_UBLOX_C027
- #define _IF(onboard,shield) onboard
+ #define MDM_IF(onboard,shield) onboard
 #else
- #define _IF(onboard,shield) shield
+ #define MDM_IF(onboard,shield) shield
 #endif
 
 //! include debug capabilty on more powerful targets with a dedicated debug port 
@@ -35,7 +35,7 @@
     //! MT Device Types 
     typedef enum { DEV_UNKNOWN, DEV_SARA_G350, DEV_LISA_U200, DEV_LISA_C200 } Dev; 
     //! SIM Status
-    typedef enum { SIM_UNKNOWN, SIM_PIN, SIM_READY } Sim;
+    typedef enum { SIM_UNKNOWN, SIM_MISSING, SIM_PIN, SIM_READY } Sim;
     //! SIM Status
     typedef enum { LPM_DISABLED, LPM_ENABLED, LPM_ACTIVE, LPM_SLEEP } Lpm; 
     //! Device status
@@ -98,7 +98,7 @@
     */
     bool connect(const char* simpin, 
             const char* apn, const char* username, const char* password,
-            PinName pn _IF( = MDMPWRON, = D4));    
+            PinName pn MDM_IF( = MDMPWRON, = D4));    
 
     /** register (Attach) the MT to the GPRS service. 
         \param simpin a optional pin of the SIM card
@@ -106,7 +106,14 @@
         \return true if successful, false otherwise
     */
     bool init(const char* simpin = NULL, DevStatus* status = NULL, 
-                PinName pn _IF( = MDMPWRON, = D4));
+                PinName pn MDM_IF( = MDMPWRON, = D4));
+    
+    /** register to the network 
+        \param status an optional structure to with network information 
+        \param timeout_ms -1 blocking, else non blocking timeout in ms
+        \return true if successful and connected to network, false otherwise
+    */
+    bool registerNet(NetStatus* status = NULL, int timeout_ms = 180000);
     
     /** check if the network is available 
         \param status an optional structure to with network information 
@@ -527,12 +534,12 @@
         \param rxSize the size of the serial rx buffer
         \param txSize the size of the serial tx buffer
     */
-    MDMSerial(PinName tx    _IF( = MDMTXD,  = D1 ), 
-              PinName rx    _IF( = MDMRXD,  = D2 ), 
-              int baudrate  _IF( = MDMBAUD, = 115200 ),
+    MDMSerial(PinName tx    MDM_IF( = MDMTXD,  = D1 ), 
+              PinName rx    MDM_IF( = MDMRXD,  = D0 ), 
+              int baudrate  MDM_IF( = MDMBAUD, = 115200 ),
  #if DEVICE_SERIAL_FC
-              PinName rts   _IF( = MDMRTS,  = NC ), 
-              PinName cts   _IF( = MDMCTS,  = NC ),
+              PinName rts   MDM_IF( = MDMRTS,  = NC /* D2 resistor R62 on shield not mounted */ ), 
+              PinName cts   MDM_IF( = MDMCTS,  = NC /* D3 resistor R63 on shield not mounted */ ),
  #endif
               int rxSize    = 256 , 
               int txSize    = 128 );
@@ -553,6 +560,7 @@
     virtual int _send(const void* buf, int len);
 };
 
+ 
 // -----------------------------------------------------------------------
 
 //#define HAVE_MDMUSB

--- a/Pipe.h	Thu May 15 22:20:42 2014 +0000
+++ b/Pipe.h	Fri May 16 14:13:00 2014 +0000
@@ -1,4 +1,5 @@
 #pragma once 
+#include "Relax.h"
 
 /** pipe, this class implements a buffered pipe that can be savely 
     written and read between two context. E.g. Written from a task 
@@ -77,7 +78,7 @@
         int j = i;
         i = _inc(i);
         while (i == _r) // = !writeable() 
-            /*wait for space*/;
+            RELAX_MS(0);
         _b[j] = c;
         _w = i; 
         return c;
@@ -100,6 +101,7 @@
                 f = free();
                 if (f > 0) break;     // data avail
                 if (!t) return n - c; // no more space and not blocking
+                RELAX_MS(0);
             }
             // check free space
             if (c < f) f = c;
@@ -144,7 +146,7 @@
     {
         int r = _r;
         while (r == _w) // = !readable()
-            /*wait for data*/;
+            RELAX_MS(0);
         T t = _b[r];
         _r = _inc(r);
         return t;
@@ -167,6 +169,7 @@
                 f = size();
                 if (f)  break;        // free space
                 if (!t) return n - c; // no space and not blocking
+                RELAX_MS(0);
             }
             // check available data
             if (c < f) f = c;

--- a/SerialPipe.cpp	Thu May 15 22:20:42 2014 +0000
+++ b/SerialPipe.cpp	Fri May 16 14:13:00 2014 +0000
@@ -39,11 +39,16 @@
         do
         {
             int written = _pipeTx.put(ptr, count, false);
-            ptr += written;
-            count -= written;
-            txStart();
+            if (written) {
+                ptr += written;
+                count -= written;
+                txStart();
+            }
+            else if (!blocking)
+                break;
+            RELAX_MS(0);
         }
-        while (count && blocking);
+        while (count);
     }
     return (length - count);
 }