drivers/audio/tea5767/tea5767.c

   1 /**************************************************************************/
   2 /*!
   3     @file     tea5767.c
   4     @author   K. Townsend
   5
   6     @brief    Driver for the TEA5767 FM receiver.
   7
   8     @section LICENSE
   9
  10     Software License Agreement (BSD License)
  11
  12     Copyright (c) 2012, K. Townsend
  13     All rights reserved.
  14
  15     Redistribution and use in source and binary forms, with or without
  16     modification, are permitted provided that the following conditions are met:
  17     1. Redistributions of source code must retain the above copyright
  18     notice, this list of conditions and the following disclaimer.
  19     2. Redistributions in binary form must reproduce the above copyright
  20     notice, this list of conditions and the following disclaimer in the
  21     documentation and/or other materials provided with the distribution.
  22     3. Neither the name of the copyright holders nor the
  23     names of its contributors may be used to endorse or promote products
  24     derived from this software without specific prior written permission.
  25
  26     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
  27     EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  28     WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  29     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
  30     DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  31     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  32     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  33     ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34     (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  35     SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36 */
  37 /**************************************************************************/
  38 #include "tea5767.h"
  39 #include "core/i2c/i2c.h"
  40 #include "core/systick/systick.h"
  41
  42 extern volatile uint8_t   I2CMasterBuffer[I2C_BUFSIZE];
  43 extern volatile uint8_t   I2CSlaveBuffer[I2C_BUFSIZE];
  44
  45 static bool _tea5767Initialised = false;
  46
  47 /**************************************************************************/
  48 /*!
  49     @brief Sends 5 bytes over I2C
  50 */
  51 /**************************************************************************/
  52 void tea5767SendData(uint8_t * bytes)
  53 {
  54   // Clear write buffers
  55   uint32_t i;
  56   for ( i = 0; i < I2C_BUFSIZE; i++ )
  57   {
  58     I2CMasterBuffer[i] = 0x00;
  59   }
  60
  61   I2CWriteLength = 6;
  62   I2CReadLength = 0;
  63   I2CMasterBuffer[0] = TEA5767_ADDRESS;
  64   I2CMasterBuffer[1] = bytes[0];
  65   I2CMasterBuffer[2] = bytes[1];
  66   I2CMasterBuffer[3] = bytes[2];
  67   I2CMasterBuffer[4] = bytes[3];
  68   I2CMasterBuffer[5] = bytes[4];
  69   i2cEngine();
  70 }
  71
  72 /**************************************************************************/
  73 /*!
  74     @brief Reads 5 bytes over I2C
  75 */
  76 /**************************************************************************/
  77 void tea5767ReadData(uint8_t * bytes)
  78 {
  79   // Clear buffers
  80   uint32_t i;
  81   for ( i = 0; i < I2C_BUFSIZE; i++ )
  82   {
  83     I2CMasterBuffer[i] = 0x00;
  84     I2CSlaveBuffer[i] = 0x00;
  85   }
  86
  87   I2CWriteLength = 1;
  88   I2CReadLength = 5;
  89   I2CMasterBuffer[0] = TEA5767_ADDRESS | TEA5767_READ;
  90   i2cEngine();
  91
  92   bytes[0] = I2CSlaveBuffer[0];
  93   bytes[1] = I2CSlaveBuffer[1];
  94   bytes[2] = I2CSlaveBuffer[2];
  95   bytes[3] = I2CSlaveBuffer[3];
  96   bytes[4] = I2CSlaveBuffer[4];
  97 }
  98
  99 /**************************************************************************/
 100 /*!
 101     @brief   This is a test function to evaluate the quality of crystals
 102              used on 3rd party modules.  Most modules use cheap 32.768kHz
 103              crystals which are prone to de-tuning.  Checking the IF bits
 104              at 81.4MHz can check if the crystal is problematic or not.
 105
 106     @returns True (1) if the IF bits are equal to 0x37 (good), otherwise
 107              false (0).  The device may still function if the IF values
 108              are slightly off, but auto-scan and tuning will likely be
 109              less reliable.
 110 */
 111 /**************************************************************************/
 112 bool tea5767CheckCrystal(void)
 113 {
 114   /*  AN10133 (p.38) states:
 115
 116       The choice of 32768Hz reference frequency makes it possible to use a
 117       cheap 32.768kHz watch crystal. A drawback of these clocks is that they
 118       have a very high second order temperature coefficient. This may result
 119       in de-tuning the radio or a search action may fail.
 120
 121       Care should be taken when using this crystal. The accuracy of the
 122       32768Hz crystal can be checked by tuning the radio to 81.4 MHz
 123       with high/low side injection and reading the IF via the bus. The IF
 124       must be 37Hex.
 125
 126       An other issue when using this crystal is the grid position. It is
 127       not possible to create a 100kHz grid position, but 98.304kHz
 128       (3*32768Hz). This should not be a problem if this is resolved in
 129       software.
 130
 131       The motional capacitance of the 32768Hz crystal should be between
 132       1.5fF and 3fF. Shunt capacitance must be max 3.5pF. The series
 133       resistance should not exceed 75KOhm.
 134
 135       Further, the frequency accuracy of this crystal must not exceed ±20
 136       ppm, while the temperature drift should be in the order of ±50 ppm
 137       over a temperature range of –10oC to +60oC.
 138   */
 139
 140   uint8_t ifValue = 0;
 141   uint8_t buffer[5] = { 0, 0, 0, 0, 0 };
 142
 143   // Set the frequency to 81.4MHz
 144   tea5767SetFrequency(81400000);
 145   systickDelay(100);
 146
 147   // Read back the IF bits
 148   tea5767ReadData(&buffer[0]);
 149   ifValue = buffer[2] & 0x7F;
 150
 151   // Reconfigure the chip to a known frequency to avoid user problems
 152   // tea5767SetFrequency(TEA5767_FMBANDSTART_JAPAN);
 153   tea5767SetFrequency(TEA5767_FMBANDSTART_US_EUROPE);
 154
 155   // Return true if the crystal is OK (IF = 0x37 @ 81.4MHz),
 156   // false if it's something else
 157   if (0x37 == ifValue)
 158     return true;
 159   else
 160     return false;
 161 }
 162
 163 /**************************************************************************/
 164 /*!
 165     @brief Initialises I2C for the TEA5767.
 166 */
 167 /**************************************************************************/
 168 uint32_t tea5767Init()
 169 {
 170   // Initialise I2C
 171   if (i2cInit(I2CMASTER) == false)
 172   {
 173     /* Fatal error */
 174     return -1;
 175   }
 176
 177   /* Set initialisation flag */
 178   _tea5767Initialised = true;
 179
 180   // Set the frequency to a known value to make sure the PLL is properly configured
 181   // tea5767SetFrequency(TEA5767_FMBANDSTART_JAPAN);
 182   tea5767SetFrequency(TEA5767_FMBANDSTART_US_EUROPE);
 183
 184   return 0;
 185 }
 186
 187 /**************************************************************************/
 188 /*!
 189     @brief  Sets the frequency to the specified value in Hz
 190
 191     @param[in]  frequency
 192                 The frequency in Hz, meaning that 95.7MHz = 97,500,000
 193                 101.4 MHz = 101,400,000 etc.
 194 */
 195 /**************************************************************************/
 196 void tea5767SetFrequency( uint32_t frequency )
 197 {
 198   uint32_t pllValue;
 199   uint8_t buffer[5] = { 0, 0, 0, 0, 0 };
 200
 201   // Make sure I2C is initialised
 202   if (!_tea5767Initialised) tea5767Init();
 203
 204   // Calculate PLL word for high side injection mode
 205   // NDEC = (4*(FRF + FIF)) / FREFS
 206   // where:
 207   // FRF = Desired tuning frequency in Hz
 208   // FIF = Intermediate frequency in Hz (225kHz)
 209   // FREFS = Reference frequency in Hz (32.768kHz)
 210   pllValue = (4 * (frequency + 225000)) / 32768;
 211
 212   buffer[0] = (pllValue >> 8) & 0x3F;              // Upper 6 PLL bits (also turns mute and search mode off!)
 213   buffer[1] = (pllValue & 0xFF);                   // Lower 8 PLL bits
 214   buffer[2] = TEA5767_WBYTE3_HLSI;                 // High side injection mode
 215   buffer[3] = TEA5767_WBYTE4_XTAL;                 // XTAL bit = 1 for 32.768kHz crystal
 216   buffer[4] = 0;                                   // PLLREF bit = 0 for 32.768kHz crystal
 217
 218   // Send data over I2C
 219   tea5767SendData(buffer);
 220 }
 221
 222 /**************************************************************************/
 223 /*!
 224     @brief  Returns the current frequency in Hz (meaning 97.5MHz will be
 225             returned as 97,500,000 etc.
 226 */
 227 /**************************************************************************/
 228 uint32_t  tea5767GetFrequency( void )
 229 {
 230   uint32_t frequency = 0;
 231   uint8_t buffer[5] = { 0, 0, 0, 0, 0 };
 232
 233   if (!_tea5767Initialised) tea5767Init();
 234
 235   tea5767ReadData(&buffer[0]);
 236
 237   // Retrieve the raw 14-bit PLL value from word 1 and 2
 238   frequency = ((buffer[0] & 0x3F) << 8) + buffer[1];
 239   // Determine the current frequency using the same high side formula as above
 240   frequency = frequency * 32768 / 4 - 225000;
 241
 242   return frequency;
 243 }
 244
 245 /**************************************************************************/
 246 /*!
 247     @brief  Starts the auto-scan process from the current frequency
 248
 249     @param[in]  scanDirection
 250                 Set this to 0 to scan down, or one to scan up, starting
 251                 at the current frequency.
 252 */
 253 /**************************************************************************/
 254 void tea5767Scan( uint8_t scanDirection )
 255 {
 256   uint8_t rbuffer[5] = { 0, 0, 0, 0, 0 };
 257   uint8_t wbuffer[5] = { 0, 0, 0, 0, 0 };
 258
 259   // Make sure I2C is initialised
 260   if (!_tea5767Initialised) tea5767Init();
 261
 262   // First we need to get the current PLL word to know where to start from
 263   tea5767ReadData(&rbuffer[0]);
 264
 265   // Set the PLL value again and append the search enable bu
 266   wbuffer[0] = TEA5767_WBYTE1_SEARCHMODE +          // Search mode enabled
 267                (rbuffer[0] & 0x3F);                 // Upper PLL bits
 268   wbuffer[1] = rbuffer[1];                          // Lower PLL bits
 269   wbuffer[2] = TEA5767_WBYTE3_SEARCHSTOPLEVEL_MID | // Mid level ADC for search steps
 270                TEA5767_WBYTE3_HLSI;                 // HLSI (must be 1 for PLL)
 271   wbuffer[3] = TEA5767_WBYTE4_XTAL;                 // Must be 1 for 32.768kHz crystal
 272   wbuffer[4] = 0x00;
 273
 274   // Set the scan direction bit to 1 (scan up) if scanDirection is non-zero
 275   if (scanDirection) wbuffer[2] |= TEA5767_WBYTE3_SEARCHUPDOWN;
 276
 277   // Send data over I2C
 278   tea5767SendData(wbuffer);
 279 }