u_cell.h

/*
 * Copyright 2019-2023 u-blox
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _U_CELL_H_
#define _U_CELL_H_

/* Only header files representing a direct and unavoidable
 * dependency between the API of this module and the API
 * of another module should be included here; otherwise
 * please keep #includes to your .c files. */

#include "u_device.h"

/** \addtogroup _cell _Cellular
 *  @{
 */

/** @file
 * @brief This header file defines the general cellular-wide APIs,
 * basically initialise and deinitialise.
 */

#ifdef __cplusplus
extern "C" {
#endif

/* ----------------------------------------------------------------
 * COMPILE-TIME MACROS
 * -------------------------------------------------------------- */

#ifndef U_CELL_UART_BUFFER_LENGTH_BYTES
/** The recommended UART buffer length for the cellular driver,
 * large enough to run AT sockets using the IP stack on the
 * cellular module (where the maximum packet length is 1024 bytes)
 * without flow control.
 *
 * The limiting factor here is being able to run in multiplexer mode,
 * which for smooth operation (i.e. not flow-controllling-off a
 * lot) benefits from allowing more room.
 */
# define U_CELL_UART_BUFFER_LENGTH_BYTES (1024 * 2)
#endif

#ifndef U_CELL_AT_BUFFER_LENGTH_BYTES
/** The AT client buffer length required in the AT client by the
 * cellular driver.
 */
# define U_CELL_AT_BUFFER_LENGTH_BYTES (U_AT_CLIENT_BUFFER_OVERHEAD_BYTES + U_CELL_UART_BUFFER_LENGTH_BYTES)
#endif

#ifndef U_CELL_UART_BAUD_RATE
/** The default baud rate to communicate with a cellular module.
 */
# define U_CELL_UART_BAUD_RATE 115200
#endif

/** There can be an inverter in-line between an MCU pin
 * and a cellular module pin; OR this value with the value
 * of a pin passed into this API and the sense of that pin
 * will be assumed to be inverted, so "asserted" will be
 * 0 and "deasserted" 1.  This method of indicating inversion
 * is preferred to the compile time options given below,
 * which are retained for backwards-compatibility.
 */
#define U_CELL_PIN_INVERTED 0x8000

/** There can be an inverter in-line between the MCU pin
 * that is connected to the cellular module's PWR_ON pin;
 * this allows the sense to be switched at compile time.
 * However, the method of ORing the pin with
 * #U_CELL_PIN_INVERTED is preferred; this compile-time
 * mechanism is retained for backwards-compatibility.
 * DON'T USE BOTH MECHANISMS or the sense of the pin will
 * be inverted twice.
 */
#ifndef U_CELL_PWR_ON_PIN_INVERTED
# define U_CELL_PWR_ON_PIN_TOGGLE_TO_STATE 0
#else
# define U_CELL_PWR_ON_PIN_TOGGLE_TO_STATE 1
#endif

/** There can be an inverter in-line between the MCU pin
 * and the thing (for example a transistor) that is enabling power to
 * the cellular module; this macro allows the sense of the power
 * on pin to be switched at compile time.  However, the
 * method of ORing the pin with #U_CELL_PIN_INVERTED is
 * preferred; this compile-time mechanism is retained for
 * backwards-compatibility.
 * DON'T USE BOTH MECHANISMS or the sense of the pin will
 * be inverted twice.
 */
#ifndef U_CELL_ENABLE_POWER_PIN_INVERTED
# define U_CELL_ENABLE_POWER_PIN_ON_STATE 1
#else
# define U_CELL_ENABLE_POWER_PIN_ON_STATE 0
#endif

/** There can be an inverter in-line between the VINT pin
 * on the cellular module and the MCU pin; this allows the sense
 * to be switched at compile time.  However, the
 * method of ORing the pin with #U_CELL_PIN_INVERTED is
 * preferred; this compile-time mechanism is retained for
 * backwards-compatibility.
 * DON'T USE BOTH MECHANISMS or the sense of the pin will
 * be inverted twice.
 */
#ifndef U_CELL_VINT_PIN_INVERTED
# define U_CELL_VINT_PIN_ON_STATE 1
#else
# define U_CELL_VINT_PIN_ON_STATE 0
#endif

#ifndef U_CELL_POWER_SAVING_UART_INACTIVITY_TIMEOUT_SECONDS
/** The time for which the cellular module's UART should remain
 * responsive after the previous command.  For SARA-R4 the value
 * is fixed at 6 seconds and hence, for convenience, a value of
 * 6 seconds is used here (for the other cellular modules) to
 * achieve the same behaviour.  Must be set to at least 1, since
 * the wake-up function is called just before the timeout.
 */
# define U_CELL_POWER_SAVING_UART_INACTIVITY_TIMEOUT_SECONDS 6
#endif


#ifndef U_CELL_POWER_SAVING_UART_WAKEUP_MARGIN_MILLISECONDS
/** The time within #U_CELL_POWER_SAVING_UART_INACTIVITY_TIMEOUT_SECONDS
 * at which this code should comme commence the "please be awake"
 * procedure, rather than just expecting the AT interface to
 * be responsive.
 */
# define U_CELL_POWER_SAVING_UART_WAKEUP_MARGIN_MILLISECONDS 500
#endif

/* ----------------------------------------------------------------
 * TYPES
 * -------------------------------------------------------------- */

/** Error codes specific to cellular.
 */
typedef enum {
    U_CELL_ERROR_FORCE_32_BIT = 0x7FFFFFFF,  /**< Force this enum to be 32 bit as it can be
                                                  used as a size also. */
    U_CELL_ERROR_AT = U_ERROR_CELL_MAX,      /**< -256 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_NOT_CONFIGURED = U_ERROR_CELL_MAX - 1, /**< -257 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_PIN_ENTRY_NOT_SUPPORTED = U_ERROR_CELL_MAX - 2, /**< -258 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_NOT_REGISTERED = U_ERROR_CELL_MAX - 3, /**< -259 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_ATTACH_FAILURE = U_ERROR_CELL_MAX - 4, /**< -260 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_CONTEXT_ACTIVATION_FAILURE = U_ERROR_CELL_MAX - 5, /**< -261 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_CONNECTED = U_ERROR_CELL_MAX - 6,  /**< This is an ERROR code used, for instance, to
                                                         indicate that a disconnect attempt has failed.
                                                         -262 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_NOT_CONNECTED = U_ERROR_CELL_MAX - 7, /**< -263 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_NOT_FOUND = U_ERROR_CELL_MAX - 8,  /**< -264 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_VALUE_OUT_OF_RANGE = U_ERROR_CELL_MAX - 9,  /**< -265 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_TEMPORARY_FAILURE = U_ERROR_CELL_MAX - 10,  /**< -266 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_CELL_LOCATE = U_ERROR_CELL_MAX - 11,  /**< -267 if #U_ERROR_BASE is 0. */
    U_CELL_ERROR_NOT_ALLOWED = U_ERROR_CELL_MAX - 12  /**< -268 if #U_ERROR_BASE is 0. */
} uCellErrorCode_t;

/* ----------------------------------------------------------------
 * FUNCTIONS
 * -------------------------------------------------------------- */

/** Initialise the cellular driver.  If the driver is already
 * initialised then this function returns immediately.
 *
 * @return zero on success or negative error code on failure.
 */
int32_t uCellInit();

/** Shut-down the cellular driver.  All cellular instances
 * will be removed internally with calls to uCellRemove().
 */
void uCellDeinit();

/** Add a cellular instance.  Note that the pin numbers
 * are those of the MCU: if you are using an MCU inside
 * a u-blox module the IO pin numbering for the module
 * is likely different to that from the MCU: check the
 * data sheet for the module to determine the mapping.
 *
 * @param moduleType       the cellular module type.
 * @param atHandle         the handle of the AT client to use.  This must
 *                         already have been created by the caller with
 *                         a buffer of size #U_CELL_AT_BUFFER_LENGTH_BYTES.
 *                         If a cellular instance has already been added
 *                         for this atHandle an error will be returned.
 * @param pinEnablePower   the pin that switches on the power
 *                         supply to the cellular module. The
 *                         Sense of the pin should be such that
 *                         low means off and high means on.
 *                         Set to -1 if there is no such pin.  If there
 *                         is an inverter between the pin of this MCU
 *                         and whatever is switching the power, so that
 *                         0 indicates "on" rather than 1, then the value
 *                         of pinEnablePower should be ORed with
 *                         #U_CELL_PIN_INVERTED.
 * @param pinPwrOn         the pin that signals power-on to the
 *                         cellular module, the pin that is connected
 *                         to the module's PWR_ON pin.
 *                         Set to -1 if there is no such pin.  If there
 *                         is an inverter between the pin of this MCU
 *                         and the PWR_ON pin of the module then the value
 *                         of pinPwrOn should be ORed with #U_CELL_PIN_INVERTED.
 * @param pinVInt          the pin that can be monitored to detect
 *                         that the cellular module is powered up.
 *                         This pin should be connected to the
 *                         VInt pin of the module and is used to
 *                         make sure that the modem is truly off before
 *                         power to it is disabled.  Set to -1 if
 *                         there is no such pin.  If there is an
 *                         inverter between the VInt pin of the module
 *                         and this pin of the MCU then the value
 *                         of pinVInt should be ORed with #U_CELL_PIN_INVERTED.
 * @param leavePowerAlone  set this to true if initialisation should
 *                         not modify the state of pinEnablePower or
 *                         pinPwrOn, else it will ensure that pinEnablePower
 *                         is low to disable power to the module and pinPwrOn
 *                         is high so that it can be pulled low to logically
 *                         power the module on.
 * @param[out] pCellHandle a pointer to the output handle. Will only be set on success.
 * @return                 zero on success or negative error code on failure.
 */
int32_t uCellAdd(uCellModuleType_t moduleType,
                 uAtClientHandle_t atHandle,
                 int32_t pinEnablePower, int32_t pinPwrOn,
                 int32_t pinVInt, bool leavePowerAlone,
                 uDeviceHandle_t *pCellHandle);

/** Remove a cellular instance.  It is up to the caller to ensure
 * that the cellular module for the given instance has been disconnected
 * and/or powered down etc.; all this function does is remove the logical
 * instance.
 *
 * @param cellHandle  the handle of the cellular instance to remove.
 */
void uCellRemove(uDeviceHandle_t cellHandle);

/** Get the handle of the AT client used by the given
 * cellular instance.
 *
 * @param cellHandle      the handle of the cellular instance.
 * @param[out] pAtHandle  a place to put the AT client handle.
 * @return                zero on success else negative error code.
 */
int32_t uCellAtClientHandleGet(uDeviceHandle_t cellHandle,
                               uAtClientHandle_t *pAtHandle);

/** \deprecated Get the delay between the end of one AT command
 * and the start of the next AT command.
 *
 * This function is deprecated and may be removed at some
 * point in the future; please use uCellAtCommandTimingGet()
 * instead.
 *
 * @param cellHandle      the handle of the cellular instance.
 * @return                on success the delay in milliseconds,
 *                        else negative error code.
 */
int32_t uCellAtCommandDelayGet(uDeviceHandle_t cellHandle);

/** \deprecated Set the delay between the end of one AT command
 * and the start of the next AT command.
 *
 * This function is deprecated and may be removed at some
 * point in the future; please use uCellAtCommandTimingSet()
 * or  uCellAtCommandTimingSetDefault() instead.
 *
 * A safe default value is set on a per-module basis but you may
 * wish to optimise the speed of exchange of AT command in your
 * product, your use-case. THIS SHOULD BE DONE WITH GREAT CARE;
 * a delay that is too short may lead to AT interface failures,
 * commands being confused with one another, etc., and these
 * issues may occur in random places, at random times, dependent
 * upon the AT command that was just executed and, potentially,
 * external factors (network searching, GNSS chip interaction,
 * etc.). You should only reduce the value from the default if
 * you have a good set of regression tests for your product
 * solution that you can run to verify that a shortened delay
 * does not introduce problems for the AT commands that you end
 * up using in the situations that you use them.
 *
 * @param cellHandle  the handle of the cellular instance.
 * @param delayMs     the minimum time from "OK" or "ERROR"
 *                    being received for one AT command to
 *                    the next AT command being issued.
 * @return            zero on success, else negative error
 *                    code.
 */
int32_t uCellAtCommandDelaySet(uDeviceHandle_t cellHandle,
                               int32_t delayMs);

/** Get the detailed timings used with the cellular module
 * at the AT interface.
 *
 * @param cellHandle                         the handle of the cellular
 *                                           instance.
 * @param[out] pDelayMs                      a place to put the delay in
 *                                           milliseconds between the end
 *                                           of one AT command and the start
 *                                           of the next AT command; may
 *                                           be NULL.
 * @param[out] pDefaultCommandTimeoutSeconds a place to put the default
      *                                      timeout, in SECONDS,
 *                                           when waiting for a response
 *                                           to an AT command; note that
 *                                           this may be modified, on a
 *                                           per command basis, by this
 *                                           code, all that is returned
 *                                           here is the value employed
 *                                           when no special circumstances
 *                                           apply; may be NULL.
 * @param[out] pUrcTimeoutMs                 a place to put the AT timeout
 *                                           that is employed when waiting
 *                                           for all of the elements of an
 *                                           unsolicited result code or URC,
 *                                           e.g. +CREG, that may arrive
 *                                           from the cellular module at
 *                                           any time (on a line-buffered
 *                                           basis); the value is in
 *                                           milliseconds, may be NULL.
 * @param[out] pReadRetryDelayMs             a place to put the delay between
 *                                           reading the AT transport channel
 *                                           and getting no data before
 *                                           retrying that read one more time;
 *                                           this avoids "stutter" on the read,
 *                                           increasing the chances that a
 *                                           complete chunk of incoming data
 *                                           is available to parse.  Value is
 *                                           in milliseconds, may be NULL.
 * @return                                   zero on success else negative error
 *                                           code.
 */
int32_t uCellAtCommandTimingGet(uDeviceHandle_t cellHandle,
                                int32_t *pDelayMs,
                                int32_t *pDefaultCommandTimeoutSeconds,
                                int32_t *pUrcTimeoutMs,
                                int32_t *pReadRetryDelayMs);

/** Set the detailed timings used with the cellular module
 * at the AT interface.  See also uCellAtCommandTimingSetDefault().
 *
 *   IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT
 *
 *                   HERE BE DRAGONS
 *
 * Default values are applied for all of these timings which
 * are tested and known to work.  You should only reduce any
 * of these values in a brief/rare period where high
 * performance/throughput is so important that it is worth
 * taking chances; reduced values may lead to the cellular
 * module missing AT commands sent to it or this code
 * missing responses from the cellular module, with AT
 * exchanges timing out or, worse, unsolicited response codes
 * (URCs) which carry vital information about the state of
 * the cellular module (e.g. registration state in +CREG and
 * the like) going missing.
 *
 * To confirm that a reduction in any of these timings has no
 * adverse effect you must be able to create regression test
 * scenarios for the relevant stress situations with your
 * product code, i.e. the AT commands that you use in the
 * worst-case situation you expect to use them.  You will
 * also need to have the relevant equipment to debug problems
 * (e.g. a Saleae probe) on the UART in real time.
 *
 * Putting it another way: don't change these values lightly.
 *
 * @param cellHandle                   the handle of the cellular
 *                                     instance.
 * @param delayMs                      the delay in milliseconds
 *                                     between the end of one AT
 *                                     command and the start of
 *                                     the next AT command; use
 *                                     -1 to leave this value
 *                                     unchanged.
 * @param defaultCommandTimeoutSeconds the default timeout, in
 *                                     SECONDS, when waiting
 *                                     for a response to an AT
 *                                     command; note that
 *                                     this may be modified, on a
 *                                     per command basis, by this
 *                                     code, this only sets the
 *                                     value employed when no
 *                                     special circumstances
 *                                     apply;  use -1 to leave
 *                                     this value unchanged.
 * @param urcTimeoutMs                 the AT timeout that is
 *                                     employed when waiting for
 *                                     all of the elements of an
 *                                     unsolicited result code or
 *                                     URC, e.g. +CREG, that may
 *                                     arrive from the cellular
 *                                     module at any time (on a
 *                                     line-buffered basis); the
 *                                     value is in milliseconds,
 *                                     use -1 to leave this value
 *                                     unchanged.
 * @param readRetryDelayMs             the delay between reading
 *                                     the AT transport channel
 *                                     and getting no data before
 *                                     retrying that read one more
 *                                     time; this avoids "stutter"
 *                                     on the read, increasing the
 *                                     chances that a complete chunk
 *                                     of incoming data is available
 *                                     to parse.  Value is in
 *                                     milliseconds, use -1 to leave
 *                                     this value unchanged.
 * @return                             zero on success else negative
 *                                     error code.
 */
int32_t uCellAtCommandTimingSet(uDeviceHandle_t cellHandle,
                                int32_t delayMs,
                                int32_t defaultCommandTimeoutSeconds,
                                int32_t urcTimeoutMs,
                                int32_t readRetryDelayMs);

/** Set the detailed timings used with the cellular module
 * to their default values.  The value of the default AT command
 * timeout and the delay between AT commands are module-specific,
 * while the value for the URC timeout will be
 * #U_AT_CLIENT_URC_TIMEOUT_MS and the value for the read retry
 * delay will be #U_AT_CLIENT_STREAM_READ_RETRY_DELAY_MS.
 *
 * @param cellHandle   the handle of the cellular instance.
 * @return             zero on success else negative error code.
 */
int32_t uCellAtCommandTimingSetDefault(uDeviceHandle_t cellHandle);

#ifdef __cplusplus
}
#endif

/** @}*/

#endif // _U_CELL_H_

// End of file