Diff: src/commI2C.cpp

Revision:

0:a91cd1b08360

Child:

2:0af50f386eb2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/commI2C.cpp	Mon Jun 18 17:31:35 2018 +0000
@@ -0,0 +1,125 @@
+#include "mbed.h"
+#include "commI2C.h"
+
+extern uint8_t buf_xmt[BUFFER_SIZE_I2C];  //outgoing data
+extern uint8_t buf_rcv[BUFFER_SIZE_I2C];  //incoming data
+I2CSlave slave(PB_9, PB_8);
+DigitalInOut wake(PA_0); 
+
+extern Serial pc;
+//#define TEST
+   
+
+//==============================================================================
+// i2c_proc_init
+// - init i2c comm to proc
+//==============================================================================     
+void i2c_proc_init()
+{   
+    slave.frequency(100000);                   // added DRT NOT NEEDED BY SLAVE????,asb, need this ????
+    uint8_t slave_address = 0xA0;                //PROC code uses 7bit address shifted by one so 0xA0 (xdot) => 0x50 (PROC)
+    slave.address(slave_address);  
+    //set wake hi 
+    
+    return;
+}
+//==============================================================================
+// i2c_wait4wake_lo
+// - wait for the wake signal from proc to go low
+// NEEDS TO BE CORRECTED, THIS WAITS FOR A HI THEN A LOW !!!!
+//==============================================================================   
+#ifdef NOT_USED  
+void i2c_wait4wake_lo(void){
+   wake.input();
+//   pc.printf("\n\r waiting for wake to go hi %d",wake);  
+   bool wakeHi=  false;
+   while(!wakeHi){               
+        wait_ms(10);  //need this wait else loop below will block previous printout
+        wakeHi =  wake;   // state of wake signal
+   }
+  // pc.printf("\n\r detected wake hi");  
+   wait_ms(100);  //need this wait else loop below will block previous printout
+ //wake signal hi,wait until it goes back lo => psoc is going to wait for ....           
+   // pc.printf("\n\r waiting for wake to go lo %d",wake);    
+    bool wakeLo = true;
+    while(wakeLo){ 
+        wait_ms(10);  //need this wait else loop below will block previous printout
+        wakeLo =  wake;   // state of wake signal
+   }
+    //pc.printf("\n\r detected wake lo "); 
+    wait_ms(100);  //wait for proc to get ready for i2c comm, proc leave wake in low state   
+    
+    
+    return;    
+}
+#endif
+//==============================================================================
+// i2c_pulse_wake
+// - pulse the wake signal to tell proc that xdot ready for i2c xfr
+//==============================================================================     
+void i2c_pulse_wake(void){
+    wake.mode(OpenDrain);
+    wake.output();
+    wake = 1;                            
+    wait_ms(10);  //proc uses interrupts on lora_wake, so don't need to wait,just pulse it
+    wake = 0;       // set wake lo  
+    wait_ms(1);  
+    wake.input();   //go back to input mode   !!! wake pull hi if go back to input mode ??? 
+    return;
+}
+//==============================================================================
+// i2c_proc_comm
+//- set WAKE low to notify proc that's OK to read/write i2c data
+//- waits FOREVER  or timeout for proc to write or read i2 data
+// - returns point to read or write i2c bfr
+//- returns true  if xdot rcvd data into buf_rcv from proc
+//          false if xdot wrote  data from buf_xmt to proc
+//- before returning sets WAKE hi
+//------------------------------------------------------------------------------
+// xdot i2c slave operation:
+// - xdot does not work correctly as a i2c slave
+// - if xdot does not respond to first incoming bytes from master (responseTime)
+//    within a defined period the xdot will hang the i2c bus until it is reset
+// - the strategy here is sit in a very tight while loop polling continually for
+//   incoming i2c bytee within the respnseTime
+// - the time around the while loop below must be < responseTime
+// - reponseTime for the while loop below is measured at 1.25 usec
+// - responseTimes upto 80 usec have been measured to be OK
+//------------------------------------------------------------------------------
+// timeout:
+// - safety mechanism to get xdot back to sleep mode if proc goes unresponsive
+// - cpu clock dependant..what mhz is cpu? presently this will give 1.1sec timout before 
+// -  0x000fffff gives a 1.1 second timeout
+// - after proc wakes xdot from sleep then proc must send an i2c omd within timout
+// - once xdot pulses wake to notify proc that i2c ack msg is ready, proc must do i2c read within timeout
+//==============================================================================
+I2C_XFR_TYPE i2c_proc_comm(void)
+{
+     bool verbose = false;    
+    uint32_t timeout = 0x000fffff;  //1.1second timeout
+  
+    while(1){
+        int i = slave.receive();  
+        switch (i) {
+            case I2CSlave::ReadAddressed:       //xdot  -> proc                     
+                slave.write((char *)buf_xmt, BUFFER_SIZE_I2C);                 
+                return I2C_WRITE;            
+            case I2CSlave::WriteAddressed:   //xdot <- proc                                                  
+                slave.read((char *)buf_rcv, BUFFER_SIZE_I2C);                 
+                if (verbose){
+                    pc.printf("\n\r Incoming buffer(hex): \n\r");                               
+                    int j;
+                    for (j = 0; j < BUFFER_SIZE_I2C; j++){
+                    pc.printf("%x", buf_rcv[j]);
+                    pc.printf(" ");
+                 }       
+                    
+                }    
+                return I2C_READ;                                          
+            default:
+        }; //switch  
+        
+        timeout--;
+        if(timeout == 0)return I2C_WRITE;  //just go to sleep 
+      }; //while  
+}             
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