+void AcquireTiType(void)
+{
+ int i;
+ int n = 5000;
+
+ // clear buffer
+ memset(BigBuf,0,sizeof(BigBuf));
+
+ // Set up the synchronous serial port
+ PIO_DISABLE = (1<<GPIO_SSC_DIN);
+ PIO_PERIPHERAL_A_SEL = (1<<GPIO_SSC_DIN);
+
+ // steal this pin from the SSP and use it to control the modulation
+ PIO_ENABLE = (1<<GPIO_SSC_DOUT);
+ PIO_OUTPUT_ENABLE = (1<<GPIO_SSC_DOUT);
+
+ SSC_CONTROL = SSC_CONTROL_RESET;
+ SSC_CONTROL = SSC_CONTROL_RX_ENABLE | SSC_CONTROL_TX_ENABLE;
+
+ // Sample at 2 Mbit/s, so TI tags are 16.2 vs. 14.9 clocks long
+ // 48/2 = 24 MHz clock must be divided by 12
+ SSC_CLOCK_DIVISOR = 12;
+
+ SSC_RECEIVE_CLOCK_MODE = SSC_CLOCK_MODE_SELECT(0);
+ SSC_RECEIVE_FRAME_MODE = SSC_FRAME_MODE_BITS_IN_WORD(32) | SSC_FRAME_MODE_MSB_FIRST;
+ SSC_TRANSMIT_CLOCK_MODE = 0;
+ SSC_TRANSMIT_FRAME_MODE = 0;
+
+ LED_D_ON();
+
+ // modulate antenna
+ PIO_OUTPUT_DATA_SET = (1<<GPIO_SSC_DOUT);
+
+ // Charge TI tag for 50ms.
+ SpinDelay(50);
+
+ // stop modulating antenna and listen
+ PIO_OUTPUT_DATA_CLEAR = (1<<GPIO_SSC_DOUT);
+
+ LED_D_OFF();
+
+ i = 0;
+ for(;;) {
+ if(SSC_STATUS & SSC_STATUS_RX_READY) {
+ BigBuf[i] = SSC_RECEIVE_HOLDING; // store 32 bit values in buffer
+ i++; if(i >= n) return;
+ }
+ WDT_HIT();
+ }
+
+ // return stolen pin ro SSP
+ PIO_DISABLE = (1<<GPIO_SSC_DOUT);
+ PIO_PERIPHERAL_A_SEL = (1<<GPIO_SSC_DIN) | (1<<GPIO_SSC_DOUT);
+}
+
+void AcquireRawBitsTI(void)
+{
+ LED_D_ON();
+ // TI tags charge at 134.2Khz
+ FpgaSendCommand(FPGA_CMD_SET_DIVISOR, 88); //134.8Khz
+ // Place FPGA in passthrough mode, in this mode the CROSS_LO line
+ // connects to SSP_DIN and the SSP_DOUT logic level controls
+ // whether we're modulating the antenna (high)
+ // or listening to the antenna (low)
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_LF_PASSTHRU);
+
+ // get TI tag data into the buffer
+ AcquireTiType();
+
+ FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);
+}
+