USRP_B210的FPGA代码分析之：B210顶层接口分析

接下来，我研究一下USRP B210的FPGA驱动程序用于移植自己的软件无线电产品。查看顶层接口代码：

/***********************************************************  * B200 Module Declaration  **********************************************************/ module b200 (    // SPI Interfaces    output   cat_ce,    input   cat_miso,    output   cat_mosi,    output   cat_sclk,     input   fx3_ce,    output   fx3_miso,    input   fx3_mosi,    input   fx3_sclk,     output   pll_ce,    output   pll_mosi,    output   pll_sclk,     // UART    // By default these provide an FX3 UART console output. Under compile time control they can alternatively    // provide 2 (1.8V) GPIO pins which are logically bits [9:8] of the fp_gpio bus.    // Used as a UART RXD is an input and TXD an output electrically.   // input   FPGA_RXD0, // These pins goto 3 pin 0.1" header on B2x0 and   // output   FPGA_TXD0, // carry FX3 UART.    inout   FPGA_RXD0, // These pins goto 3 pin 0.1" header J400 on B2x0 and    inout   FPGA_TXD0, // carry FX3 UART.     // Catalina Controls    output   codec_enable,    output   codec_en_agc,    output   codec_reset,    output   codec_sync,    output   codec_txrx,    output [3:0]  codec_ctrl_in, // These should be outputs    input [7:0]   codec_ctrl_out, // MUST BE INPUT     // Catalina Data    input   codec_data_clk_p, // Clock from CAT (RX)    output   codec_fb_clk_p, // Clock to CAT (TX)    input [11:0]  rx_codec_d,    output [11:0] tx_codec_d,    input   rx_frame_p,    output   tx_frame_p,     input   cat_clkout_fpga,     //always on 40MHz clock    input   codec_main_clk_p,    input   codec_main_clk_n,     // Debug Bus  //  output [31:0] debug,   // output [1:0]  debug_clk,     // GPIF, FX3 Slave FIFO    output   IFCLK, // pclk    input   FX3_EXTINT,    output   GPIF_CTL0, // n_slcs    output   GPIF_CTL1, // n_slwr    output   GPIF_CTL2, // n_sloe    output   GPIF_CTL3, // n_slrd    output   GPIF_CTL7, // n_pktend    input   GPIF_CTL4, // slfifo_flags[0]    input   GPIF_CTL5, // slfifo_flags[1]    input   GPIF_CTL6, // Serial settings bus from FX3. SDA    input   GPIF_CTL8, // Serial settings bus from FX3. SCL    output   GPIF_CTL11, // slfifo_addr[1]    output   GPIF_CTL12, // slfifo_addr[0]    inout [31:0]  GPIF_D,    input   GPIF_CTL9, // global_reset     // GPS    //input   gps_lock,    output   gps_rxd,    input   gps_txd, // FPGA has pullup for unpopulated GPS    //input   gps_txd_nmea, // FPGA has pullup for unpopulated GPS     // LEDS    output   LED_RX1,    output   LED_RX2,    output   LED_TXRX1_RX,    output   LED_TXRX1_TX,    output   LED_TXRX2_RX,    output   LED_TXRX2_TX,     // GPIO Header J504  - 10 pin 0.1" 3.3V.    // Only present on Rev6 and later boards...these pins unused on Rev5 and earlier.    // NOTE: These pins are allocated from complimentry pairs and could potentially be used    // as differential style I/O.   `ifdef TARGET_B210    inout [7:0]   fp_gpio,   `endif    // Misc Hardware Control    output   ref_sel,    input   pll_lock,    input   FPGA_CFG_CS, // Driven by FX3 gpio.    input   AUX_PWR_ON, // Driven by FX3 gpio.     // PPS    input   PPS_IN_EXT,    input   PPS_IN_INT,     // RF Hardware Control    output   SFDX1_RX,    output   SFDX1_TX,    output   SFDX2_RX,    output   SFDX2_TX,    output   SRX1_RX,    output   SRX1_TX,    output   SRX2_RX,    output   SRX2_TX,    output   tx_bandsel_a,    output   tx_bandsel_b,    output   tx_enable1,    output   tx_enable2,    output   rx_bandsel_a,    output   rx_bandsel_b,    output   rx_bandsel_c    );   

让我们一点一点地品尝：

适当理解USRP B对于210硬件，上述接口与实际芯片之间的连接可以很容易地对应。接下来，我们将分析每个模块、连接和逻辑。