ltc_afe.h

#pragma once
// Driver for LTC6811 AFE chip
 
// TODO(SOFT-9): Need to update GPIO/ADC part
 
// Requires GPIO, Interrupts, Soft Timers, and Event Queue to be initialized
 
// Note that all units are in 100uV.
 
// This module supports AFEs with >=12 cells using the |cell/aux_bitset|.
// Note that due to the long conversion delays required, we use an FSM to return control to the
// application.
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>
 
#include "fsm.h"
#include "gpio.h"
#include "spi.h"
#include "status.h"
 
// This is an arbitrary limitation, can be increased/decreased if needed
#define LTC_AFE_MAX_DEVICES 3
// This is a device limitation
#define LTC_AFE_MAX_CELLS_PER_DEVICE 12
#define LTC_AFE_MAX_THERMISTORS_PER_DEVICE 8
#define LTC_AFE_MAX_CELLS (LTC_AFE_MAX_DEVICES * LTC_AFE_MAX_CELLS_PER_DEVICE)
#define LTC_AFE_MAX_THERMISTORS (LTC_AFE_MAX_DEVICES * LTC_AFE_MAX_THERMISTORS_PER_DEVICE)
 
#if defined(__GNUC__)
#define _PACKED __attribute__((packed))
#else
#define _PACKED
#endif
 
// select the ADC mode (trade-off between speed or minimizing noise)
// see p.50 for conversion times and p.23 for noise
typedef enum { LTC_AFE_ADC_MODE_27KHZ = 0, LTC_AFE_ADC_MODE_7KHZ, LTC_AFE_ADC_MODE_26HZ, LTC_AFE_ADC_MODE_14KHZ, LTC_AFE_ADC_MODE_3KHZ, LTC_AFE_ADC_MODE_2KHZ, NUM_LTC_AFE_ADC_MODES } LtcAfeAdcMode;
 
typedef struct LtcAfeBitset {
  uint16_t cell_bitset;
  uint16_t aux_bitset;
} LtcAfeBitset;
 
typedef struct LtcAfeSettings {
  GpioAddress cs;
  GpioAddress mosi;
  GpioAddress miso;
  GpioAddress sclk;
 
  const SpiPort spi_port;
  uint32_t spi_baudrate;
 
  LtcAfeAdcMode adc_mode;
 
  uint16_t cell_bitset[LTC_AFE_MAX_DEVICES];
  uint16_t aux_bitset[LTC_AFE_MAX_DEVICES];
 
  size_t num_devices;
  size_t num_cells;
  size_t num_thermistors;
 
  void *result_context;
} LtcAfeSettings;
 
typedef struct LtcAfeStorage {
  // Only used for storage in the FSM so we store data for the correct cells
  uint16_t aux_index;
  uint16_t retry_count;
  uint16_t device_cell;
 
  uint16_t cell_voltages[LTC_AFE_MAX_CELLS];
  uint16_t aux_voltages[LTC_AFE_MAX_THERMISTORS];
 
  uint16_t discharge_bitset[LTC_AFE_MAX_DEVICES];
 
  uint16_t cell_result_lookup[LTC_AFE_MAX_CELLS];
  uint16_t aux_result_lookup[LTC_AFE_MAX_THERMISTORS];
  uint16_t discharge_cell_lookup[LTC_AFE_MAX_CELLS];
  uint16_t max_temp;
 
  LtcAfeSettings settings;
} LtcAfeStorage;
 
// Initialize the LTC6811.
// |settings.cell_bitset| and |settings.aux_bitset| should be an array of bitsets where bits 0 to 11
// represent whether we should monitor the cell input for the given device.
// |settings.cell_result_cb| and |settings.aux_result_cb| will be called when the corresponding
// conversion is completed.
StatusCode ltc_afe_init(LtcAfeStorage *afe, const LtcAfeSettings *settings);