1 | /* $Id: xspi_slave_polled_example.c,v 1.1.2.1 2011/08/09 06:59:27 svemula Exp $ */
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2 |
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3 | ******************************************************************************/
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4 | /*****************************************************************************/
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5 | /**
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6 | * @file xspi_slave_polled_example.c
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7 | *
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8 | * This file contains a design example using the Spi driver (XSpi) and the SPI
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9 | * device as a Slave, in polled mode.
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10 | *
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11 | * This example fills the Spi Tx buffer with the number of data bytes it expects
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12 | * to receive from the master and then Spi device waits for an external master to
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13 | * initiate the transfer. When the master initiates the transfer, the Spi device
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14 | * receives data from the master and simultaneously sends the data in Tx buffer
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15 | * to the master. Once the transfer is complete, this example prints the data
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16 | * received from the master. The number of bytes to be received by the Spi slave
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17 | * is defined by the constant BUFFER_SIZE in this file.
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18 | *
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19 | * The external SPI devices that are present on the Xilinx boards don't support
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20 | * the Master functionality. This example has been tested with an off board
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21 | * external SPI Master device and the Xilinx SPI device configured as a Slave.
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22 | * This example has been tested for byte-wide SPI transfers.
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23 | *
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24 | * @note
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25 | *
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26 | * This example assumes that there is a STDIO device in the system.
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27 | *
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28 | *<pre>
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29 | * MODIFICATION HISTORY:
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30 | *
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31 | * Ver Who Date Changes
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32 | * ----- ---- -------- ---------------------------------------------------------
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33 | * 1.00a psk 09/05/08 First Release
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34 | * 3.00a ktn 10/28/09 Converted all register accesses to 32 bit access.
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35 | * Updated to use the HAL APIs/macros. Replaced call to
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36 | * XSpi_Initialize API with XSpi_LookupConfig and
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37 | * XSpi_CfgInitialize.
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38 | *
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39 | *</pre>
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40 | ******************************************************************************/
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41 |
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42 | /***************************** Include Files *********************************/
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43 |
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44 | #include "xparameters.h" /* XPAR parameters */
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45 | #include "xspi.h" /* SPI device driver */
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46 | #include "stdio.h"
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47 |
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48 | /************************** Constant Definitions *****************************/
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49 |
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50 | /*
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51 | * The following constants map to the XPAR parameters created in the
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52 | * xparameters.h file. They are defined here such that a user can easily
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53 | * change all the needed parameters in one place.
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54 | */
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55 | #define SPI_DEVICE_ID XPAR_SPI_0_DEVICE_ID
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56 |
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57 | /*
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58 | * This is the size of the buffer to be transmitted/received in this example.
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59 | */
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60 | #define BUFFER_SIZE 16
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61 |
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62 | /**************************** Type Definitions *******************************/
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63 |
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64 |
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65 | /***************** Macros (Inline Functions) Definitions *********************/
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66 |
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67 |
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68 | /************************** Function Prototypes ******************************/
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69 |
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70 | static int SpiSlavePolledExample(XSpi *SpiInstancePtr, u16 SpiDeviceId);
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71 |
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72 | /************************** Variable Definitions *****************************/
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73 |
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74 | /*
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75 | * The instances to support the device drivers are global such that they are
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76 | * initialized to zero each time the program runs. They could be local but
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77 | * should at least be static so that they are zeroed.
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78 | */
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79 | static XSpi SpiInstance; /* The instance of the SPI device */
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80 |
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81 | /*
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82 | * The following variables are used to read from the Spi device, these are
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83 | * global to avoid having large buffers on the stack.
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84 | */
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85 | u8 ReadBuffer[BUFFER_SIZE];
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86 | u8 WriteBuffer[BUFFER_SIZE];
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87 | u16 ReadBuffer1;
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88 |
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89 | /*
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90 | * The following variable allows a test value to be added to the values that
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91 | * are sent in reflection to the Master transmission such that unique values can
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92 | * be generated to guarantee the transfer from Slave to Master is successful.
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93 | */
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94 | int Test;
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95 |
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96 | /*****************************************************************************/
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97 | /**
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98 | *
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99 | * Main function to call the Spi Slave example in polled mode.
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100 | *
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101 | * @param None
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102 | *
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103 | * @return XST_SUCCESS if successful, otherwise XST_FAILURE.
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104 | *
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105 | * @note None
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106 | *
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107 | ******************************************************************************/
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108 | int main(void)
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109 | {
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110 | int Status;
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111 |
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112 | /*
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113 | * Run the Spi Slave polled example.
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114 | */
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115 |
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116 | Status = SpiSlavePolledExample(&SpiInstance, SPI_DEVICE_ID);
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117 | if (Status != XST_SUCCESS) {
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118 | return XST_FAILURE;
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119 |
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120 |
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121 | }
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122 | return XST_SUCCESS;
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123 | }
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124 |
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125 | /*****************************************************************************/
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126 | /**
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127 | *
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128 | * This function does a minimal test on the Spi device and driver as a design
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129 | * example. The purpose of this function is to illustrate the device slave
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130 | * functionality in polled mode. This function receives data from a master and
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131 | * prints the received data.
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132 | *
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133 | * @param SpiInstancePtr is a pointer to the instance of Spi component.
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134 | *
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135 | * @param SpiDeviceId is the Device ID of the Spi Device and is the
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136 | * XPAR_<SPI_instance>_DEVICE_ID value from xparameters.h.
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137 | *
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138 | * @return XST_SUCCESS if successful, otherwise XST_FAILURE.
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139 | *
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140 | * @note This function contains an infinite loop such that if the Spi
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141 | * device doesn't receive any data, it may never return.
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142 | *
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143 | ******************************************************************************/
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144 | int SpiSlavePolledExample(XSpi *SpiInstancePtr, u16 SpiDeviceId)
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145 | {
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146 | XSpi_Config *ConfigPtr;
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147 | int Status;
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148 | u32 Count;
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149 |
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150 | xil_printf("\r\nEntering the Spi Slave Polled Example.\r\n");
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151 | xil_printf("Waiting for data from SPI master\r\n");
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152 |
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153 | /*
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154 | * Initialize the SPI driver so that it's ready to use, specify the
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155 | * device ID that is generated in xparameters.h.
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156 | */
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157 | ConfigPtr = XSpi_LookupConfig(SpiDeviceId);
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158 | if (ConfigPtr == NULL) {
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159 | return XST_FAILURE;
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160 | }
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161 | Status = XSpi_CfgInitialize(SpiInstancePtr, ConfigPtr,
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162 | ConfigPtr->BaseAddress);
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163 | if (Status != XST_SUCCESS) {
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164 | return XST_FAILURE;
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165 | }
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166 |
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167 |
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168 |
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169 |
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170 | /*
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171 | * The SPI device is a slave by default and the clock phase and polarity
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172 | * have to be set according to its master. In this example, CPOL is set
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173 | * to active low and CPHA is set to 1.
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174 | */
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175 | Status = XSpi_SetOptions(SpiInstancePtr, XSP_CLK_PHASE_1_OPTION |
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176 | XSP_CLK_ACTIVE_LOW_OPTION);
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177 | if (Status != XST_SUCCESS) {
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178 | return XST_FAILURE;
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179 | }
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180 |
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181 | /*
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182 | * Start the SPI driver so that the device is enabled.
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183 | */
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184 | XSpi_Start(SpiInstancePtr);
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185 |
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186 | /*
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187 | * Disable Global interrupt to use polled mode operation.
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188 | */
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189 | XSpi_IntrGlobalDisable(SpiInstancePtr);
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190 |
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191 |
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192 | /*
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193 | * Prepare the data buffers for transmission and to send/receive data
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194 | * when the SPI device is selected by a master.
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195 | */
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196 | while(1)
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197 | {
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198 | XSpi_Transfer(SpiInstancePtr, 0xF012, ReadBuffer1, 2);
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199 | xil_printf("0x%x \r\n", ReadBuffer1);
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200 | }
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201 |
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202 |
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203 |
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204 | return XST_SUCCESS;
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205 | }
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