Infineon AIROC CYW9 907 Series User manual

Application note
Please read the sections “Important notice” and “Warnings” at the end of this document
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www.infineon.com
2023-05-11
AN237426
AIROC™ CYW9x907 Wi-Fi connectivity processor
low-power modes
About this document
Scope and purpose
This application note introduces low-power modes in AIROC™ CYW9x907 Wi-Fi connectivity processors and
describes how to adjust the build of an application to use low-power modes.
Intended audience
This application note is for anyone who uses low-power support for an application running on one of the
following kits:
1. CYW943907AEVAL1F
2. CYW954907AEVAL1F

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
Table of contents
Table of contents
About this document....................................................................................................................... 1
Table of contents............................................................................................................................ 2
1Introduction .......................................................................................................................... 3
2Low-power mode features ...................................................................................................... 4
2.1 Application processor (APP CPU) ...........................................................................................................4
2.2 Wireless LAN processor (WLAN CPU)......................................................................................................4
3APP CPU low-power mode settings........................................................................................... 5
3.1 Sleep ........................................................................................................................................................5
3.2 DeepSleep................................................................................................................................................5
3.2.1 DeepSleep latency .............................................................................................................................5
3.3 Hibernation..............................................................................................................................................5
4WLAN CPU low-power modes................................................................................................... 7
4.1 Default WLAN low-power mode..............................................................................................................7
4.2 PM1 powersave mode.............................................................................................................................7
4.3 PM2 powersave mode.............................................................................................................................7
5HAL functions ........................................................................................................................ 8
5.1 Single-threaded application...................................................................................................................8
5.1.1 Single-threaded application using SW1 interrupt ............................................................................8
5.1.2 Single-threaded application using tickless Sleep or DeepSleep......................................................9
5.2 Multi-threaded applications .................................................................................................................10
5.3 Lock/Unlock DeepSleep........................................................................................................................10
References....................................................................................................................................11
Revision history.............................................................................................................................12
Disclaimer.....................................................................................................................................13

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
Introduction
1Introduction
The AIROC™ CYW9x907 Wi-Fi connectivity processor supports all rates specified in the IEEE 802.11 b/g/n
specifications and includes an Arm® Cortex®-based applications processor, a single-stream IEEE 802.11n
MAC/baseband/radio, a dual-band (2.4 GHz/5 GHz) transmit power amplifier (PA), and a receive low noise
amplifier (LNA). Figure 1 shows the interconnections of all the major physical blocks in CYW43907 and their
associated external interfaces.
CYW43907 functional block diagram

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
Low-power mode features
2Low-power mode features
This MCU platform has two CPUs:
1. Application processor (APP CPU)
2. Wireless LAN processor (WLAN CPU)
Power modes for both the CPUs are independent and can be used together or separately.
2.1 Application processor (APP CPU)
The APP CPU runs the user application. Two sleep modes (Sleep and DeepSleep) are used to reduce power by
halting the processor for short periods of time. This is done automatically in conjunction with the RTOS.
Additionally, the CPI has the Hibernation low-power mode, which stops the processor for a specified time and
reboots it when the hibernation time is expired.
2.2 Wireless LAN processor (WLAN CPU)
The WLAN CPU is a separate CPU that communicates to the APP CPU through the M2M DMA interface, and
controls the Wi-Fi radio. The APP CPU does not directly control the WLAN CPU; it only sends and receives
commands and data. The WLAN CPU has its own internal low-power methodology. From the APP CPU, the
application can send a command to indicate that the WLAN CPU is allowed to go into a low-power mode when
it chooses do so. In addition, the application can send a request to select the low-power mode that the WLAN
CPU uses.

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
APP CPU low-power mode settings
3APP CPU low-power mode settings
The setting for the APP CPU low-power mode is in <app_root_directory>/bsps/
TARGET_APP_CYW943907AEVAL1F/cybsp.h.
Table 1 APP CPU low-power settings
3.1 Sleep
Sleep halts the processor and reduces the power consumption by approximately 5% until there is an interrupt
which brings the system back to full power. When enabled, the RTOS determines when the user application
would be idle, and puts the APP CPU into sleep mode, reducing the overall power consumption.
3.2 DeepSleep
DeepSleep stops the system clock and reduces the power consumption by 75% until there is an interrupt which
brings the system back to full power. When enabled, the RTOS determines when the application would be idle,
and puts the APP CPU into DeepSleep mode, reducing the overall power consumption.
3.2.1 DeepSleep latency
The latency is used to determine whether there is a reasonably long enough time to go into DeepSleep, and is
measured in milliseconds. This is only used in multi-threaded applications using an RTOS. The RTOS
determines how much time there is before the next task runs. If that time exceeds the latency value, the system
goes into DeepSleep mode.
3.3 Hibernation
Hibernation uses an external source to wake the system. When hibernating, the device shuts down all
peripherals and reduces the power consumption to the lowest possible value while still retaining some control
as to when the device wakes up. This means that the current state of the device (RAM, etc.) is lost. Table 2
indicates the hibernation wakeup source. The code needed to enter Hibernation mode is shown in Code Listing
2.
Define
Notes
CY_CFG_PWR_MODE_ACTIVE
Active mode –do not go into any sleep mode
CY_CFG_PWR_MODE_SLEEP
Sleep mode –reduce power by putting processor to sleep
CY_CFG_PWR_MODE_DEEPSLEEP
DeepSleep –Sleep mode + stop the system clock
CY_CFG_PWR_DEEPSLEEP_LATENCY
Number of ticks required before going into DeepSleep
Code Listing 1 Power mode setting in cybsp.h
#define CY_CFG_PWR_MODE_ACTIVE (0x00UL)
#define CY_CFG_PWR_MODE_SLEEP (0x01UL)
#define CY_CFG_PWR_MODE_DEEPSLEEP (0x02UL)
#ifndef CY_CFG_PWR_SYS_IDLE_MODE
#define CY_CFG_PWR_SYS_IDLE_MODE (CY_CFG_PWR_MODE_ACTIVE)
#endif
#define CY_CFG_PWR_DEEPSLEEP_LATENCY (24UL) /* Min. 24 for this device */

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
APP CPU low-power mode settings
Table 2 Hibernation wakeup source
Define
Notes
CYHAL_SYSPM_HIBERNATE_WDT
Configures the WDT interrupt as the wakeup source.
This is the only wakeup source currently supported.
Code Listing 2 Calling hibernate from main()
#include "cyhal_syspm.h"
cy_rslt_t result;
result = cyhal_syspm_hibernate(cyhal_syspm_hibernate_source_t wakeup_source);

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
WLAN CPU low-power modes
4WLAN CPU low-power modes
The WLAN CPU runs a fixed firmware image that is loaded at power-up of the device. The WLAN CPU runs
independently of the APP CPU and talks to the APP CPU through a dedicated M2M DMA channel. The
application running on the APP CPU can send commands to the WLAN CPU that allows the WLAN CPU to
determine when to go into a low-power mode.
Table 3 WLAN CPU power mode settings
4.1 Default WLAN low-power mode
The default for WLAN low-power mode is CY_WCM_NO_POWERSAVE_MODE. To change modes, the application
must call the function to allow the WLAN to change power mode.
4.2 PM1 powersave mode
This mode saves the most power at the expense of some data throughput. The integrity of the Wi-Fi connection
is not compromised, but some operations may take slightly longer than in “no powersave” mode.
4.3 PM2 powersave mode
This mode saves less power than PM1, but keeps the data throughput at a higher level. The integrity of the Wi-Fi
connection is not compromised
Define
Description
CY_WCM_NO_POWERSAVE_MODE
No power savings.
CY_WCM_PM1_POWERSAVE_MODE
Powersave mode on specified interface without regard for
throughput reduction.
CY_WCM_PM2_POWERSAVE_MODE
Powersave mode on specified interface with high
throughput.
Code Listing 3 Allowing WLAN power modes in the user application
#include "cy_wcm.h"
Cy_rslt_t result;
result = cy_wcm_allow_low_power_mode(CY_WCM_PM1_POWERSAVE_MODE);

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
HAL functions
5HAL functions
The Hardware Abstraction Layer (HAL) API provides functions for applications to affect the power mode of the
device. See Hardware Abstraction Layer power management API for more information.
When Sleep or DeepSleep occurs, the code hits an Arm® Cortex®-R4 “Stop and Wait for Interrupt” (SWI)
instruction. This instruction halts the processor until an interrupt allows it to continue.
5.1 Single-threaded application
Single-threaded applications do not use an RTOS, and must call the sleep functions directly. The application
must also provide a way for the APP CPU to resume.
5.1.1 Single-threaded application using SW1 interrupt
Do the following to use the button marked “SW1”on the CYW943907AEVAL1F board to trigger an interrupt that
wakes up the APP CPU from Sleep or DeepSleep:
1. Enable an SW1 event to produce an interrupt when pressed.
3. Press SW1 on the board to exit Sleep or DeepSleep.
Code Listing 4 Enable button press for interrupt to wake from Sleep/DeepSleep
#include "cyhal_gpio.h"
/* Configure GPIO button for an interrupt to wake from sleep / deepsleep. */
cyhal_gpio_init(CYBSP_SW1, CYHAL_GPIO_DIR_INPUT, CYHAL_GPIO_DRIVE_PULLUP,
CYBSP_BTN_OFF);
cyhal_gpio_enable_event(CYBSP_SW1, CYHAL_GPIO_IRQ_FALL, 7, true);
2. Call the Sleep (or DeepSleep) function.
Code Listing 5 Calling the Sleep function
#include "cyhal_syspm.h"
/* Call sleep –must wake through interrupt */
cyhal_syspm_sleep();
Code Listing 6 Calling the DeepSleep function
#include "cyhal_syspm.h"
/* Call deepsleep –must wake through interrupt */
cyhal_syspm_deepsleep();

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
HAL functions
5.1.2 Single-threaded application using tickless Sleep or DeepSleep
The following code listings show the steps to use the low-power timer (lptimer) and the tickless sleep functions
to enable the APP CPU to enter Sleep or DeepSleep mode for a specified time. The APP CPU Sleep mode may
end earlier than the specified time due to an interrupt. The value returned in the actual_sleep_ms argument
reflects the time (in milliseconds) that the APP CPU was in Sleep or DeepSleep mode.
1. Initialize the low-power timer to use tickless Sleep or DeepSleep.
2. Put the APP CPU into Sleep or DeepSleep.
The device wakes up after the specified desired_ms time.
Code Listing 7 Initializing the low-power timer
#include "cyhal_lptimer.h"
cyhal_lptimer_t lptimer;
/* Initialize the low power timer */
cyhal_lptimer_init(&lptimer);
Code Listing 8 Using tickles Sleep
uint32_t desired_ms;
uint32_t actual_sleep_ms;
/* Call tickless sleep –will wake after specified time */
desired_ms = 1000;
cyhal_syspm_tickless_sleep(&lptimer, desired_ms, &actual_sleep_ms);
Code Listing 9 Using tickless DeepSleep
uint32_t desired_ms;
uint32_t actual_sleep_ms;
/* Call tickless deepsleep –will wake after specified time */
desired_ms = 1000;
cyhal_syspm_tickless_deepsleep(&lptimer, desired_ms, &actual_sleep_ms);

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HAL functions
5.2 Multi-threaded applications
In multi-threaded applications, the user application does not call the sleep functions directly. They are called
from the RTOS in the idle task. Code Listing 10 and Code Listing 11 show how to enable the RTOS to call Sleep
and DeepSleep mode.
5.3 Lock/Unlock DeepSleep
If the user application needs a thread to delay, but does not want to put the device into DeepSleep, call lock
and unlock around the protected code.
Use the following functions to lock or unlock DeepSleep:
•cyhal_syspm_lock_deepsleep():This function disallows the device from entering DeepSleep until the
unlock function is called. The function uses a counter so that multiple threads can call this function. Until all
threads unlock DeepSleep, the device will not go into DeepSleep.
•cyhal_syspm_unlock_deepsleep(): This function decrements the counter. When all threads have called
unlock, the RTOS can initiate putting the device into DeepSleep when the correct conditions are met.
Code Listing 10 Enable RTOS to Sleep during APP CPU idle
<root of application>/bsps/TARGET_APP_CYW954907AEVAL1F/cybsp.h
#ifndef CY_CFG_PWR_SYS_IDLE_MODE
#define CY_CFG_PWR_SYS_IDLE_MODE (CY_CFG_PWR_MODE_SLEEP)
#endif
Code Listing 11 Enable RTOS to call DeepSleep during APP CPU idle
<root of application>/bsps/TARGET_APP_CYW954907AEVAL1F/cybsp.h
#ifndef CY_CFG_PWR_SYS_IDLE_MODE
#define CY_CFG_PWR_SYS_IDLE_MODE (CY_CFG_PWR_MODE_DEEPSLEEP)
#endif
#define CY_CFG_PWR_DEEPSLEEP_LATENCY (24UL) /* Min. 24 for this device */
Code Listing 12 Locking DeepSleep
/* Lock device from entering deepsleep for this section of code */
cyhal_syspm_lock_deepsleep();
/*
* Deepsleep will not occur in this section of code
*/
/* Allow deepsleep again */
cyhal_syspm_unlock_deepsleep();

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References
References
[1] Hardware Abstraction Layer Power Management API
[2] Infineon AN214828 Power Consumption Measurements Application Note
[3] Low Power Current Measurements Using CYW943907AEVAL1F

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AIROC™ CYW9x907 Wi-Fi connectivity processor low-power modes
Revision history
Revision history
Document
revision
Date
Description of changes
**
2023-05-11
Initial release.

Important notice
Warnings
Edition 2023-05-11
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2023 Infineon Technologies AG.
All Rights Reserved.
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