Diff: CC1101/CC1101-FreqScan.cpp

Revision:

1:05a48c038381

Parent:

0:c5afea7b9057

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/CC1101/CC1101-FreqScan.cpp	Sun Dec 28 06:28:42 2014 +0000
@@ -0,0 +1,147 @@
+#include "CC1101.h"
+
+#define CC_NUMBER_OF_SUB_BANDS 1
+
+uint16_t CC1101::scan(void)
+{
+    int8_t i;
+    int16_t channel;
+
+    uint8_t rssi_offset = 74;
+    carrierSenseCounter = 0;
+
+    uint8_t lastChannel = 10;
+    uint16_t limitTest0Reg = 0;
+    int16_t highRSSI = -150;
+    uint16_t selectedChannel = 25;
+
+
+// Freq. Band Range Channel
+// 0 779.009766 - 829.997314 0 - 255 All 0x0B
+// 1 830.196869 - 881.184418 0 - 255 <- 154 = 0x0B, 155 -> = 0x09
+// 2 881.384369 - 927.972992 0 - 233 All 0x09
+    /*
+        uint8_t freqSettings[CC_NUMBER_OF_SUB_BANDS][3] = {{0x1D, 0xF6, 0x40},
+            {0x1F, 0xEE, 0x3F},
+            {0x21, 0xE6, 0x3F}
+        };
+    */
+
+
+// 1.1) Set the base freq. for the current sub band. The values for FREQ2, FREQ1, and FREQ0 can be found in
+// freqSettings[subBand][n], where n = 0, 1, or 2
+    /*
+    for (int n=0; n<3; n++) {
+        write_reg(CCxxx0_FREQ2 + n, freqSettings[subBand][n]);
+    }
+    */
+
+    uint8_t calCounter = 0;
+
+    // 1.4.2.1) Set TEST0 register = 0x09
+    write_reg(CCxxx0_TEST0, 0x09);
+
+    // 1.4.2.2) Set FSCAL2 register = 0x2A
+    write_reg(CCxxx0_FSCAL2, 0x2A);
+
+
+    // 1.3) Loop through all channels
+    for (channel = 0; channel <= lastChannel; channel++ ) {
+        int8_t pktStatus;
+
+        // 1.3.1) Set CHANNR register = channel
+        write_reg(CCxxx0_CHANNR, channel);
+
+        // 1.4.3) Calibrate for every 4th ch. + at start of every sub band and every time the TEST0 reg. is changed
+        if (calCounter++ == 0) {
+            // 1.4.3.1) Perform a manual calibration by issuing an SCAL strobe command
+            calibrate();
+        }
+
+
+        // 1.4.4)) Reset Calibration Counter (if calCounter = 5, we are 1 MHz away from the frequency where a
+        // calibration was performed)
+        if (calCounter == 4) {
+            // 1.4.4.1) Calibration is performed if calCounter = 0
+            calCounter = 0;
+        }
+
+
+        // 1.3.3) Enter RX mode by issuing an SRX strobe command
+        rx_mode();
+
+        // 1.3.4) Wait for radio to enter RX state (can be done by polling the MARCSTATE register)
+        while(mode() != 0x0D);
+
+        // 1.3.5) Wait for RSSI to be valid (See DN505 [7] on how long to wait)
+        wait(0.4);
+
+        // 1.3.6) Read the PKTSTATUS register while the radio is in RX state (store it in pktStatus)
+        pktStatus = status(CCxxx0_PKTSTATUS);
+
+        // 1.3.7) Enter IDLE state by issuing an SIDLE strobe command
+        strobe(CCxxx0_SIDLE);
+
+        // 1.3.8) Check if CS is asserted (use the value obtained in 1.3.6)
+        if (pktStatus & 0x40) { // CS is asserted
+
+            // 1.3.8.1) Read RSSI value and store it in rssi_dec
+            rssi_dec = status(CCxxx0_RSSI);
+
+            // 1.3.8.2) Calculate RSSI in dBm (rssi_dBm)(offset value found in rssi_offset)
+            if (rssi_dec & 0x80) {
+                rssi_dBm = (rssi_dec - 256)>>1;  // negate and divide by 2
+            } else {
+                rssi_dBm = rssi_dec>>1; // divide by 2
+            }
+            rssi_dBm -= rssi_offset;  // offset adjustment
+
+
+            std::printf("RSSI: %d\r\n", rssi_dBm);
+            // 1.3.8.3) Store the RSSI value and the corresponding channel number
+            rssiTable[carrierSenseCounter] = rssi_dBm;
+            channelNumber[carrierSenseCounter] = channel;
+            carrierSenseCounter++;
+        }
+    } // End Channel Loop
+
+
+    // 1.4) Before moving on to the next sub band, scan through the rssiTable to find the highest RSSI value. Store
+    // the RSSI value in highRSSI and the corresponding channel number in selectedChannel
+    for (i = 0; i < carrierSenseCounter; i++) {
+        if (rssiTable[i] > highRSSI) {
+            highRSSI = rssiTable[i];
+            selectedChannel = channelNumber[i];
+        }
+    }
+
+
+    // 1.5) Reset carrierSenseCounter
+    //  carrierSenseCounter = 0;
+
+// } // End Band Loop
+
+    /*
+
+    // 2) When all sub bands have been scanned, find which sub band has the highest RSSI (Scan the highRSSI[subBand]
+    // table). Store the subBand (0, 1, or 2) and the corresponding channel in the global variables activeBand and
+    // activeChannel respectively
+    int16_t tempRssi = -150;
+    // for (int subBand = 0; subBand < CC_NUMBER_OF_SUB_BANDS; subBand++)
+    // {
+        if (highRSSI >= tempRssi) {
+            tempRssi = highRSSI;
+            activeChannel = selectedChannel;
+            activeBand = subBand;
+        }
+    // }
+
+    */
+
+    activeChannel = selectedChannel;
+
+    std::printf("Active Channel: %u\r\nRSSI: %ddBm\r\n", activeChannel, highRSSI);
+
+    return activeChannel;
+
+}
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