Rick McConney / sfh7779

Gsma Version

Dependents:   GSMACode stripReader

pca9548.h@1:fc2dbccffe34, 2017-04-21 (annotated)

Committer:
elmkom
Date:
Fri Apr 21 17:58:08 2017 +0000
Revision:
1:fc2dbccffe34
Parent:
0:5e15a306a518 
Proximity strip reader

Who changed what in which revision?

UserRevisionLine numberNew contents of line
elmkom 0:5e15a306a518 1 // NXP PCA9548: 8-channel I2C switch with reset
elmkom 0:5e15a306a518 2
elmkom 0:5e15a306a518 3 #define PCA9548_BASE_ADDR_7BIT 0x70
elmkom 0:5e15a306a518 4
elmkom 0:5e15a306a518 5 #define MAX_CHANNELS 8
elmkom 0:5e15a306a518 6
elmkom 0:5e15a306a518 7 #define ASSERT_RESET 0
elmkom 0:5e15a306a518 8 #define NEGATE_RESET 1
elmkom 0:5e15a306a518 9
elmkom 0:5e15a306a518 10 class PCA9548
elmkom 0:5e15a306a518 11 {
elmkom 0:5e15a306a518 12 public:
elmkom 0:5e15a306a518 13 /**
elmkom 0:5e15a306a518 14 * Constructor
elmkom 0:5e15a306a518 15 *
elmkom 0:5e15a306a518 16 * @param i2c I2C class servicing the multiplexer
elmkom 0:5e15a306a518 17 * @param addr_3bit address of the multiplexer (A0-A2 pin strapping)
elmkom 0:5e15a306a518 18 * Valid values are 0-7
elmkom 0:5e15a306a518 19 * @param reset optional DigitalOut class that resets the multiplexer (disables all I2C channels)
elmkom 0:5e15a306a518 20 * Not needed if hardware reset is not used or if reset
elmkom 0:5e15a306a518 21 * is not managed by the class.
elmkom 0:5e15a306a518 22 */
elmkom 0:5e15a306a518 23 PCA9548(I2C * i2c, uint8_t addr_3bit, DigitalOut * reset = NULL) : _i2c(i2c), _reset(reset) {
elmkom 0:5e15a306a518 24 _addr_8bit = ((addr_3bit & 0x7) + PCA9548_BASE_ADDR_7BIT) << 1;
elmkom 0:5e15a306a518 25 }
elmkom 0:5e15a306a518 26
elmkom 0:5e15a306a518 27 /**
elmkom 0:5e15a306a518 28 * Reset the multiplexer. All devices connected to the downstream side of
elmkom 0:5e15a306a518 29 * the multiplexer are removed from the I2C bus. If hardware reset is being
elmkom 0:5e15a306a518 30 * used, reset is done via asserting the reset pin. Otherwise, reset is
elmkom 0:5e15a306a518 31 * accomplished by deselecting all channels through soft configuration.
elmkom 0:5e15a306a518 32 *
elmkom 0:5e15a306a518 33 * @returns true if successful
elmkom 0:5e15a306a518 34 */
elmkom 0:5e15a306a518 35 bool reset(void) {
elmkom 0:5e15a306a518 36 if (_reset) {
elmkom 0:5e15a306a518 37 _reset->write(ASSERT_RESET);
elmkom 0:5e15a306a518 38 return true;
elmkom 0:5e15a306a518 39 } else {
elmkom 0:5e15a306a518 40 const char channel = 0;
elmkom 0:5e15a306a518 41 return _i2c->write(_addr_8bit, &channel, 1) == 0;
elmkom 0:5e15a306a518 42 }
elmkom 0:5e15a306a518 43 }
elmkom 0:5e15a306a518 44
elmkom 0:5e15a306a518 45 /**
elmkom 0:5e15a306a518 46 * Enable access to one of the eight devices on the downstream side of
elmkom 0:5e15a306a518 47 * the multiplexer.
elmkom 0:5e15a306a518 48 *
elmkom 0:5e15a306a518 49 * @param channel channel to activate. Valid values are 0-7.
elmkom 0:5e15a306a518 50 *
elmkom 0:5e15a306a518 51 * @returns true if successful
elmkom 0:5e15a306a518 52 */
elmkom 0:5e15a306a518 53 bool select_channel(const uint8_t channel) {
elmkom 0:5e15a306a518 54 if (channel < MAX_CHANNELS) {
elmkom 0:5e15a306a518 55 char channel_mask = 1 << channel;
elmkom 0:5e15a306a518 56 if (_reset) {
elmkom 0:5e15a306a518 57 _reset->write(NEGATE_RESET);
elmkom 0:5e15a306a518 58 }
elmkom 0:5e15a306a518 59 return _i2c->write(_addr_8bit, (const char *)&channel_mask, 1) == 0;
elmkom 0:5e15a306a518 60 } else {
elmkom 0:5e15a306a518 61 return false;
elmkom 0:5e15a306a518 62 }
elmkom 0:5e15a306a518 63 }
elmkom 0:5e15a306a518 64
elmkom 0:5e15a306a518 65 protected:
elmkom 0:5e15a306a518 66 int _addr_8bit;
elmkom 0:5e15a306a518 67 I2C * _i2c;
elmkom 0:5e15a306a518 68 DigitalOut * _reset;
elmkom 0:5e15a306a518 69 };