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Merged
merged 3 commits into from
Aug 19, 2025
Merged

Apollo3: Simplify and standardize pin modes #485

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1d851a5
Apollo3: Simplify and standardize pin modes
multiplemonomials Aug 18, 2025
c2f648b
A few tweaks
multiplemonomials Aug 18, 2025
07386bd
Add docs
multiplemonomials Aug 18, 2025
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1 change: 1 addition & 0 deletions platform/source/mbed_board.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ WEAK MBED_NORETURN void mbed_die(void)

#ifdef LED1
gpio_t led_err;
memset(&led_err, 0, sizeof(gpio_t));
gpio_init_out(&led_err, LED1);
#endif

Expand Down
132 changes: 48 additions & 84 deletions targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/gpio_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,8 @@
#include "gpio_api.h"
#include "PeripheralPins.h"

#include <string.h>

/** Set the given pin as GPIO
*
* @param pin The pin to be set as GPIO
Expand Down Expand Up @@ -66,94 +68,50 @@ void gpio_init(gpio_t *obj, PinName pin)
void gpio_mode(gpio_t *obj, PinMode mode)
{
MBED_ASSERT(gpio_is_connected(obj));
MBED_ASSERT(mode < (PinMode)PinModeElements);
am_hal_gpio_pincfg_allow_t pinConfigBools = {0};

obj->cfg.uFuncSel = AP3_PINCFG_FUNCSEL_GPIO; // gpio

if (mode & (PinMode)PowerSwNone) {
obj->cfg.ePowerSw = AM_HAL_GPIO_PIN_POWERSW_NONE;
pinConfigBools.ePowerSw = true;
}
if (mode & (PinMode)PowerSwVDD) {
obj->cfg.ePowerSw = AM_HAL_GPIO_PIN_POWERSW_VDD;
pinConfigBools.ePowerSw = true;
}
if (mode & (PinMode)PowerSwVSS) {
obj->cfg.ePowerSw = AM_HAL_GPIO_PIN_POWERSW_VSS;
pinConfigBools.ePowerSw = true;
}
// Configure pull-up or pull-down
pinConfigBools.ePullup = true;

if (mode & (PinMode)PullNone) {
if(!(mode & OpenDrain) && obj->isOutput) {
// Push-pull output, do not allow pullup
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_NONE;
pinConfigBools.ePullup = true;
}
if (mode & (PinMode)PullUp) {
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_WEAK;
pinConfigBools.ePullup = true;
}
if (mode & (PinMode)PullDown) {
else if (mode & (PinMode)PullUp) {
MBED_ASSERT(obj->pad != IO_20); // pullup not supported on IO 20

if(obj->pad == IO_0 || obj->pad == IO_1 || obj->pad == IO_5 || obj->pad == IO_6 || obj->pad == IO_8
|| obj->pad == IO_9 || obj->pad == IO_25 || obj->pad == IO_27 || obj->pad == IO_39 ||
obj->pad == IO_40 || obj->pad == IO_42 || obj->pad == IO_43 || obj->pad == IO_48 || obj->pad == IO_49) {
// These pads (with I2C support) need a different constant to get the same resistance
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_24K;
}
else{
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_WEAK;
}
}
else if (mode & (PinMode)PullDown) {
MBED_ASSERT(obj->pad == IO_20); // pulldown only supported on IO 20
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLDOWN;
pinConfigBools.ePullup = true;
}

if (mode & (PinMode)DriveStrength2mA) {
obj->cfg.eDriveStrength = AM_HAL_GPIO_PIN_DRIVESTRENGTH_2MA;
pinConfigBools.eDriveStrength = true;
}
if (mode & (PinMode)DriveStrength4mA) {
obj->cfg.eDriveStrength = AM_HAL_GPIO_PIN_DRIVESTRENGTH_4MA;
pinConfigBools.eDriveStrength = true;
}
if (mode & (PinMode)DriveStrength8mA) {
obj->cfg.eDriveStrength = AM_HAL_GPIO_PIN_DRIVESTRENGTH_8MA;
pinConfigBools.eDriveStrength = true;
}
if (mode & (PinMode)DriveStrength12mA) {
obj->cfg.eDriveStrength = AM_HAL_GPIO_PIN_DRIVESTRENGTH_12MA;
pinConfigBools.eDriveStrength = true;
}

if (mode & (PinMode)OutDisable) {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_DISABLE;
pinConfigBools.eGPOutcfg = true;
}
if (mode & (PinMode)OutPushPull) {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
pinConfigBools.eGPOutcfg = true;
}
if (mode & (PinMode)OutOpenDrain) {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_OPENDRAIN;
pinConfigBools.eGPOutcfg = true;
}
if (mode & (PinMode)OutTristate) {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_TRISTATE;
pinConfigBools.eGPOutcfg = true;
else {
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_NONE;
}

if (mode & (PinMode)InAuto) {
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_AUTO;
pinConfigBools.eGPInput = true;
}
if (mode & (PinMode)InNone) {
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_NONE;
pinConfigBools.eGPInput = true;
// Configure output type
obj->openDrain = mode & OpenDrain;
pinConfigBools.eGPOutcfg = true;
if(obj->isOutput) {
obj->cfg.eGPOutcfg = obj->openDrain ? AM_HAL_GPIO_PIN_OUTCFG_OPENDRAIN : AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
}
if (mode & (PinMode)InEnable) {
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_ENABLE;
pinConfigBools.eGPInput = true;
else {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_DISABLE;
}

if (mode & (PinMode)ReadPin) {
obj->cfg.eGPRdZero = AM_HAL_GPIO_PIN_RDZERO_READPIN;
pinConfigBools.eGPRdZero = true;
}
if (mode & (PinMode)ReadZero) {
obj->cfg.eGPRdZero = AM_HAL_GPIO_PIN_RDZERO_ZERO;
pinConfigBools.eGPRdZero = true;
}

ap3_hal_gpio_pinconfig_partial((uint32_t)(obj->pad), obj->cfg, pinConfigBools); //padRegMsk.byte, GPConfigMsk.byte, padAltCfgMsk.byte); // apply configuration
MBED_ASSERT(ap3_hal_gpio_pinconfig_partial((uint32_t)(obj->pad), obj->cfg, pinConfigBools) == AM_HAL_STATUS_SUCCESS);
}

/** Set the pin direction
Expand All @@ -167,23 +125,33 @@ void gpio_dir(gpio_t *obj, PinDirection direction)
MBED_ASSERT(direction < (PinDirection)PIN_DIR_ELEMENTS);
am_hal_gpio_pincfg_allow_t pinConfigBools= {0};

// Always enable the input on the pin, so that we can read it if it is open drain.
pinConfigBools.eGPInput = true;
pinConfigBools.eGPRdZero = true;
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_ENABLE;
obj->cfg.eGPRdZero = AM_HAL_GPIO_PIN_RDZERO_READPIN;

if (direction == (PinDirection)PIN_INPUT) {
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_ENABLE;
pinConfigBools.eGPInput = true;
obj->isOutput = false;
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_DISABLE;
pinConfigBools.eGPOutcfg = true;
} else if (direction == (PinDirection)PIN_OUTPUT) {
obj->cfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
obj->isOutput = true;
obj->cfg.eGPOutcfg = obj->openDrain ? AM_HAL_GPIO_PIN_OUTCFG_OPENDRAIN : AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
pinConfigBools.eGPOutcfg = true;
obj->cfg.eDriveStrength = AM_HAL_GPIO_PIN_DRIVESTRENGTH_12MA;
pinConfigBools.eDriveStrength = true;
obj->cfg.eGPInput = AM_HAL_GPIO_PIN_INPUT_NONE;
pinConfigBools.eGPInput = true;

// Clear any configured pullup if set to open-drain
if(!obj->openDrain) {
pinConfigBools.ePullup = true;
obj->cfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_NONE;
}
} else {
MBED_ASSERT(false);
}

ap3_hal_gpio_pinconfig_partial((uint32_t)(obj->pad), obj->cfg, pinConfigBools); //padRegMsk.byte, GPConfigMsk.byte, padAltCfgMsk.byte); // apply configuration
ap3_hal_gpio_pinconfig_partial((uint32_t)(obj->pad), obj->cfg, pinConfigBools);
}

/** Set the output value
Expand All @@ -205,12 +173,8 @@ void gpio_write(gpio_t *obj, int value)
int gpio_read(gpio_t *obj)
{
MBED_ASSERT(gpio_is_connected(obj));
uint32_t ui32BaseAddr = (obj->pad) / 8;
uint32_t ui32BaseShift = (((obj->pad) % 8) * 4) + 1;
uint8_t output = ((AM_REGVAL(&GPIO->CFGA + ui32BaseAddr) >> ui32BaseShift) & 0x03);

return (output) ? (int)am_hal_gpio_output_read(obj->pad) : (int)am_hal_gpio_input_read(obj->pad);
return 0;
return am_hal_gpio_input_read(obj->pad);
}

/** Get the pins that support all GPIO tests
Expand Down
83 changes: 17 additions & 66 deletions targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/objects_gpio.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,78 +43,29 @@ typedef enum {
PIN_DIR_ELEMENTS
} PinDirection;

enum sPinMode {
sPowerSwNone = 0x00,
sPowerSwVDD,
sPowerSwVSS,
sPullNone,
sPullUp,
sPullDown,
sPullUp1K5,
sPullUp6K,
sPullUp12K,
sPullUp24K,
sDriveStrength2mA,
sDriveStrength4mA,
sDriveStrength8mA,
sDriveStrength12mA,
sOutDisable,
sOutPushPull,
sOutOpenDrain,
sOutTristate,
sInAuto,
sInNone,
sInEnable,
sReadPin,
sReadZero,

sPinModeElements
};

#define PinModeEntry(e) e = (1 << s##e)

typedef enum {
PinModeEntry(PowerSwNone),
PinModeEntry(PowerSwVDD),
PinModeEntry(PowerSwVSS),
PowerSwDefault = PowerSwNone,

PinModeEntry(PullNone),
PinModeEntry(PullUp),
PinModeEntry(PullDown),
PinModeEntry(PullUp1K5),
PinModeEntry(PullUp6K),
PinModeEntry(PullUp12K),
PinModeEntry(PullUp24K),
PullDefault = PullNone,

PinModeEntry(DriveStrength2mA),
PinModeEntry(DriveStrength4mA),
PinModeEntry(DriveStrength8mA),
PinModeEntry(DriveStrength12mA),
DriveStrengthDefault = DriveStrength12mA,

PinModeEntry(OutDisable),
PinModeEntry(OutPushPull),
PinModeEntry(OutOpenDrain),
PinModeEntry(OutTristate),
OutDefault = OutPushPull,

PinModeEntry(InAuto),
PinModeEntry(InNone),
PinModeEntry(InEnable),
InDefault = InEnable,

PinModeEntry(ReadPin),
PinModeEntry(ReadZero),
ReadDefault = ReadPin,

PinModeEntry(PinModeElements)

PullNone = 0,

// Supported on all IOs except IO 20. Actual resistance 13-27kOhm
PullUp = 1 << 0,

// Only supported on IO 20, Actual resistance 26-40kOhm
PullDown = 1 << 1,

OpenDrain = 1 << 2,
OpenDrainPullUp = OpenDrain | PullUp, ///< Open-drain mode with pull up. Supported on all IOs except IO 20.
OpenDrainPullDown = OpenDrain | PullDown, ///< Open-drain mode with pull down. Only supported on IO 20.
OpenDrainNoPull = OpenDrain, ///< Open-drain mode with no pullup/pulldown. Supported on all IOs.

PullDefault = PullNone
} PinMode;

typedef struct _gpio_t {
ap3_gpio_pad_t pad;
am_hal_gpio_pincfg_t cfg;
bool openDrain;
bool isOutput;
} gpio_t;

typedef struct ap3_gpio_irq_control_t {
Expand Down