Configuration¶

The values the driver needs about your board, where each one is set, and the compile-time defaults behind them.

Run-time settings¶

Setting	Set with	Default	Sent to the chip
Reference voltage (REFP)	constructor `vref`, `SetVref()`	`DEFAULT_VREF`, 2.5 V	No: conversion only
Analog supply (+VA)	constructor `va`, `SetVA()`	`DEFAULT_VA`, 5.0 V	No: stored for your use (`GetVA()`)
Input range	constructor `initial_range`, `SetRange()`	`DEFAULT_RANGE`, `Range::Vref`	Yes, in effect when `SetRange()` returns
Auto-1 mask	`ProgramAuto1Channels()`	`DEFAULT_AUTO1_MASK`, `0x0FFF`	Yes, by `EnsureInitialized()`
Auto-2 last channel	`ProgramAuto2LastChannel()`	`DEFAULT_AUTO2_LAST_CH`, 11	Yes, by `EnsureInitialized()`
Power-down	`SetPowerDown()`	`PowerDown::Normal`	Yes, in effect when `SetPowerDown()` returns
GPIO functions and outputs	`ProgramGPIO()`, `SetGPIOOutputs()`	all inputs	Yes

The constructor's initial_range sets the driver's full scale only. The chip starts in the 0 to VREF range after power-up and takes Range::TwoVref with the Auto-1 mode frame that EnsureInitialized() sends.

// Auto-1 scans any subset; Auto-2 scans CH0..last. Program them once after EnsureInitialized().
if (!adc.ProgramAuto1Channels(ads7952::ChannelMask(0, 1, 4, 5))) {
  return false;
}
if (!adc.ProgramAuto2LastChannel(7)) {               // CH0..CH7
  return false;
}

// 0..2 x VREF: only valid while 2 x VREF <= +VA (2.5 V reference, 5 V supply).
if (!adc.SetRange(ads7952::Range::TwoVref)) {        // in effect on the chip when it returns
  return false;
}

Reference and range¶

The active reference is VREF in Range::Vref and 2 × VREF in Range::TwoVref. A count converts as count × active reference / 4095.

Range	Measurable span	Condition (datasheet)
`Range::Vref`	0 V to VREF	VREF 2.0 V to 3.0 V
`Range::TwoVref`	0 V to 2 × VREF	2 × VREF ≤ +VA

Clamping of vref and va

The constructor, SetVref() and SetVA() clamp their arguments to the datasheet's recommended operating conditions (SLAS605C section 7.3): ADS7952_CFG::MIN_VREF ... MAX_VREF is 2.0 V to 3.0 V and MIN_VA ... MAX_VA is 2.7 V to 5.25 V. A vref outside 2.0 V to 3.0 V is converted with the nearest limit.

The driver does not limit Range::TwoVref to +VA: with 2.5 V at REFP, use it only on a 5 V analog supply.

Compile-time defaults¶

inc/ads7952_config.hpp defines the defaults in the ADS7952_CFG namespace. Each can be overridden with a define, from Kconfig in ESP-IDF or from CMake:

Define	Constant	Default	Effect
`CONFIG_ADS7952_VREF_MV`	`DEFAULT_VREF`	2500	Constructor default for `vref`, in mV
`CONFIG_ADS7952_VA_MV`	`DEFAULT_VA`	5000	Constructor default for `va`, in mV
`CONFIG_ADS7952_RANGE_2VREF`	`DEFAULT_RANGE`	not set (`Range::Vref`)	Defined: `Range::TwoVref`
`CONFIG_ADS7952_AUTO1_CHANNEL_MASK`	`DEFAULT_AUTO1_MASK`	`0x0FFF`	Mask `EnsureInitialized()` programs
`CONFIG_ADS7952_AUTO2_LAST_CH`	`DEFAULT_AUTO2_LAST_CH`	11	Last channel `EnsureInitialized()` programs
`CONFIG_ADS7952_MANUAL_READ_MAX_FRAMES`	`MANUAL_READ_MAX_FRAMES`	4	Continue frames `ReadChannel()` tries
`CONFIG_ADS7952_READ_ALL_MAX_EXTRA`	`READ_ALL_MAX_EXTRA_FRAMES`	4	Spare frames for `ReadAllChannels()`
`CONFIG_ADS7952_MODE_AUTO1`, `_AUTO2`	`DEFAULT_MODE`	Manual	Defined but not used by the driver
`CONFIG_ADS7952_MAX_RETRIES`	`MAX_RETRIES`	3	Defined but not used by the driver

target_compile_definitions(my_app PRIVATE
    CONFIG_ADS7952_VREF_MV=2048
    CONFIG_ADS7952_AUTO1_CHANNEL_MASK=0x000F)   # CH0..CH3

The defines must be visible wherever ads7952.hpp is included; set them on the target, not in one source file. ESP-IDF has no Kconfig file for the driver: add the options to your project's Kconfig with these names and sdkconfig.h provides the CONFIG_ macros.

Where the defaults come from¶

Each value is in inc/ads7952_config.hpp and in the API reference; the chip's own reset state (Manual mode, CH0, range 1, all GPIOs inputs) is in the datasheet, Tables 1 to 13.