ads1115 v0.1.0

ADS1115 16-bit I2C analog-to-digital converter.

Application scenarios

• A precision sensor with a small analog output.
• Battery or supply voltage measurement.
• A bridge or thermistor front end.

Contract

typedef enum {
    ADS1115_RANGE_6P144V = 0,
    ADS1115_RANGE_4P096V,
    ADS1115_RANGE_2P048V,
    ADS1115_RANGE_1P024V,
    ADS1115_RANGE_0P512V,
    ADS1115_RANGE_0P256V,
} ads1115_range_t;

uint8_t ads1115_init(ads1115_t *device, ads1115_port_t port, uint8_t i2c_address);
uint8_t ads1115_read_single(ads1115_t *device, uint8_t channel,
                            ads1115_range_t range, int16_t *raw, int32_t *microvolts);

• channel is 0..3 (single-ended AIN0..AIN3).
• read_single starts a single conversion, waits 10 ms, and reads the result.
• microvolts is the signed input voltage in microvolts.
• Returns 1 on success, 0 on a bad argument or a bus error.

Parameters

• I2C address 0x48..0x4B from ADDR.
• Range sets the full scale; the LSB is range / 32768.
• The input must stay within the selected range.

Memory and timing

• 4 bytes; one 2-byte config write and one 2-byte conversion read.
• 128 samples/s; a single read takes about 8 ms.

Integration

ads1115_t adc;
int16_t raw;
int32_t microvolts;
ads1115_init(&adc, board_i2c_port(), 0x48);
ads1115_read_single(&adc, 0, ADS1115_RANGE_4P096V, &raw, &microvolts);

Adapters

• The adapter issues a register write followed by a repeated-start read.
• Reference: LibDriver ads1115 (MIT) and the Texas Instruments ADS1115 datasheet.
• This implementation is original.

When not to use

• A ratiometric MCU ADC is enough; use the internal ADC.
• Differential measurements with a strict common-mode limit; check the datasheet.

Verification

make test covers the config word, positive and negative conversion,

range scaling, and channel validation.

ADS1115_RANGE_6P144V = 0,
ADS1115_RANGE_4P096V,
ADS1115_RANGE_2P048V,
ADS1115_RANGE_1P024V,
ADS1115_RANGE_0P512V,
ADS1115_RANGE_0P256V,

void *context;
uint8_t (*write)(void *context, uint8_t address, uint8_t reg,
const uint8_t *data, uint16_t length);
uint8_t (*read)(void *context, uint8_t address, uint8_t reg,
uint8_t *data, uint16_t length);
void (*delay_ms)(void *context, uint16_t milliseconds);

ads1115_port_t port;
uint8_t i2c_address;