How to speed up the change between PTX and PRX of esb?

[chianglin]

Hi,

I am using 2 esb devices to test my packet send and received.

My use case is:

1. Node-1 and Node-2 is power-in in PRX mode

2. Node-1 switch to PTX and send a packet, then switch to PRX,

3. Node-2 receive packet, switch to PTX mode and send a packet out. After send packet, switch to PRX.

4. Node-1 receive packet, switch to PTX mode and send a packet out. After send packet, switch to PRX.

....

If the speed between PTX and PRX is to fast, then it will cause many "Send error".  If I add some delay (Ex: use nrf_delay_ms(2)), then there will no error occur.

What is the bottleneck? PTX switch to PRX? or PRX switch to PTX?

Thank you,

Chianglin

[ovrebekk]

Hi Chianglin

In principle it should take less than 200us to switch from PTX to PRX or vice versa. 

The question is whether or not you are able to switch in sync. If the PTX has switched before the PRX then the packet you send will not be successfully received. 

Are you using ACK's or retransmits?

If you are using the retransmit feature then any lost packet should be automatically retransmitted, so that you don't see it as a packet loss. 

Best regards
Torbjørn

[chianglin]

Hi Torbjørn,

Actually, the ack function had been disable in my case.

Please reference the attach file, there have two dependent project which need to download to two different device (name: Host and Node).

Fullscreen Host.c Download

#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include "sdk_common.h"
#include "nrf.h"
#include "nrf_esb.h"
#include "nrf_error.h"
#include "nrf_esb_error_codes.h"
#include "nrf_delay.h"
#include "nrf_gpio.h"
#include "boards.h"
#include "nrf_delay.h"
#include "app_util.h"
#include "app_timer.h"
#include "nrf_drv_gpiote.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#include "GpioProcess.h"
#include "EsbProcess.h"

#define	Host_SendBack										// �w�q�o���ܼ� -> Host ����ʥ]��, �|���@�U���e, �M��A�o�^�h

unsigned long	PacketSendCnt = 0;
unsigned long	PacketSendOKCnt = 0;
unsigned long	PacketSentNGCnt = 0;
unsigned long	PacketReceiveOKCnt = 0;
unsigned long	PacketReceiveNGCnt = 0;

void PacketSend(void)
{
    int							i;
    uint8_t						Sum = 0;

	//	printf(" ==> Send Packet back\r\n");
#if 1
	EebTxRxSwitch(TX);
#else
	(void) nrf_esb_stop_rx();
	(void) nrf_esb_flush_tx();
	(void) nrf_esb_start_tx();
#endif
	for (i = 1 ; i < NRF_ESB_MAX_PAYLOAD_LENGTH ; i++ )
		Sum = Sum + tx_payload.data[i];
	tx_payload.data[0] = Sum;
    tx_payload.noack = true;
    if (nrf_esb_write_payload(&tx_payload) == NRF_SUCCESS)
    {
        tx_payload.data[2]++;
    #ifdef	EsbTestUartEnsable
		printf(" [%X %X %X %X %X %X %X %X]\r\n", tx_payload.length, tx_payload.pipe, tx_payload.rssi, tx_payload.noack, tx_payload.pid, tx_payload.data[0], tx_payload.data[1], tx_payload.data[2]);
    	printf(" Send. CheckSum =  %X\r\n", Sum);
        printf(" Send OK\r\n");
    #endif	// EsbTestUartEnsable
    }
    else
    {
        //	printf(" *** Sending packet failed");
    } 
}

long	RxLedFlashCnt = 0;
void nrf_esb_event_handler(nrf_esb_evt_t const * p_event)
{
    switch (p_event->evt_id)
    {
        case NRF_ESB_EVENT_TX_SUCCESS:
        	PacketSendOKCnt++;
        #ifdef	EsbTestUartEnsable
        	printf(" Change to RX\r\n");
        #endif	// EsbTestUartEnsable
        	EebTxRxSwitch(RX);
        	break;
        case NRF_ESB_EVENT_TX_FAILED:
        	//	printf(" TX-Err\r\n");
            (void) nrf_esb_flush_tx();
            (void) nrf_esb_start_tx();
            PacketSentNGCnt++;
            tx_payload.data[3]++;
            nrf_delay_ms(2);
            PacketSend();
            break;
        case NRF_ESB_EVENT_RX_RECEIVED:
        #ifdef	EsbTestUartEnsable
            printf("RX RECEIVED PAYLOAD\r\n");
        #endif	// EsbTestUartEnsable
            while (nrf_esb_read_rx_payload(&rx_payload) == NRF_SUCCESS)
            {
            #ifdef	Host_SendBack
                if (rx_payload.length > 0)
                {
	            	uint8_t			Sum = 0;
            		int				i;
            		for ( i = 1 ; i < NRF_ESB_MAX_PAYLOAD_LENGTH ; i++ )
            			Sum = Sum + rx_payload.data[i];
					if ( Sum == rx_payload.data[0] )
					{
						PacketReceiveOKCnt++;
						//	printf(" I [%X]\r\n", Sum);
						if ( ++RxLedFlashCnt == 50 )
						{
							RxLedFlashCnt = 0;
							nrf_gpio_pin_toggle(GpioLed0);
						}
					}
					else
					{
						PacketReceiveNGCnt++;
                    	printf(" *** Packet NG [%x]---\r\n", Sum);
                    }
                    // ���� PTX, �e�ʥ]
                    memcpy(tx_payload.data, rx_payload.data, rx_payload.length);
                    tx_payload.data[3]++;
                    nrf_delay_ms(2);
					PacketSend();
		            //	PacketSend(rx_payload.data[1]);
                }
            #endif	// Host_SendBack
            }
            break;
    }
}


void clocks_start( void )
{
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART = 1;

    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
}

unsigned char	TriggerPressed = 0;
unsigned char	TriggerPressedFlag = 0;

// ---- APP_TIMER code added here ----
APP_TIMER_DEF(m_esb_tx_timer_id);
APP_TIMER_DEF(Timer_1S_timer_id);

void Action_Key1(void)
{
	PacketSend();
}
	
void esb_send_packet_timer_callback(void *p)
{
	PacketSend();
}

extern	uint8_t		KeyDebunseTick;
void Timer_1S(void *p)
{
	static uint32_t		sPacketSendOKCnt, sPacketSentNGCnt, sPacketReceiveOKCnt, sPacketReceiveNGCnt;
	printf(" TX: %d/%d, RX: %d/%d\r\n", (PacketSendOKCnt - sPacketSendOKCnt), (PacketSentNGCnt - sPacketSentNGCnt), (PacketReceiveOKCnt - sPacketReceiveOKCnt), (PacketReceiveNGCnt - sPacketReceiveNGCnt));
	sPacketSendOKCnt = PacketSendOKCnt;
	sPacketSentNGCnt = PacketSentNGCnt;
	sPacketReceiveOKCnt = PacketReceiveOKCnt;
	sPacketReceiveNGCnt = PacketReceiveNGCnt;
}

static void timers_init(void)
{
	ret_code_t err_code;
    
	// Start the 32.768 kHz low frequency clock. Without this the app_timer module won't work
	NRF_CLOCK->TASKS_LFCLKSTART = 1;
    
	// Initialize timer module.
	err_code = app_timer_init();
	APP_ERROR_CHECK(err_code); 

	// Create timers.
	err_code = app_timer_create(&m_esb_tx_timer_id, APP_TIMER_MODE_REPEATED, esb_send_packet_timer_callback);
	APP_ERROR_CHECK(err_code);
	err_code = app_timer_create(&Timer_1S_timer_id, APP_TIMER_MODE_REPEATED, Timer_1S); 
	APP_ERROR_CHECK(err_code);
}

static void timers_start(void)
{
    ret_code_t err_code;
#if 0
    err_code = app_timer_start(m_esb_tx_timer_id, APP_TIMER_TICKS(3000/*100*/), (void *)0);
    APP_ERROR_CHECK(err_code);
#endif
    err_code = app_timer_start(Timer_1S_timer_id, APP_TIMER_TICKS(5000/*100*/), (void *)0);
    APP_ERROR_CHECK(err_code);
}
// -----------------------------------


int main(void)
{
    ret_code_t err_code;

    clocks_start();
    gpio_init();
    UART_Init();
    printf(" ... Start (TX) ...\r\n");
    timers_init();
    
    err_code = esb_init(RX);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_esb_start_rx();
    APP_ERROR_CHECK(err_code);

    timers_start();

	while(1)
	{
        if(NRF_LOG_PROCESS() == false)
        {
            __WFE();
        }
	}
    while (true)
    {
        // Nothing to do now that the app_timer runs everything, except flush the log and go to sleep
        if(NRF_LOG_PROCESS() == false)
        {
            __WFE();
        }
    }
}

Fullscreen Node.c Download

#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include "sdk_common.h"
#include "nrf.h"
#include "nrf_esb.h"
#include "nrf_error.h"
#include "nrf_esb_error_codes.h"
#include "nrf_delay.h"
#include "nrf_gpio.h"
#include "boards.h"
#include "nrf_delay.h"
#include "app_util.h"
#include "app_timer.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"

#include "GpioProcess.h"
#include "EsbProcess.h"

unsigned long	PacketSendCnt = 0;
unsigned long	PacketSendOKCnt = 0;
unsigned long	PacketSentNGCnt = 0;
unsigned long	PacketReceiveOKCnt = 0;
unsigned long	PacketReceiveNGCnt = 0;

void PacketSend(void)
{
    int							i;
    uint8_t						Sum = 0;

	//	printf(" ==> Send Packet back\r\n");
#if 1
	EebTxRxSwitch(TX);
#else
	(void) nrf_esb_stop_rx();
	(void) nrf_esb_flush_tx();
	(void) nrf_esb_start_tx();
#endif
	for (i = 1 ; i < NRF_ESB_MAX_PAYLOAD_LENGTH ; i++ )
		Sum = Sum + tx_payload.data[i];
	tx_payload.data[0] = Sum;
    tx_payload.noack = true;
    if (nrf_esb_write_payload(&tx_payload) == NRF_SUCCESS)
    {
        tx_payload.data[2]++;
    #ifdef	EsbTestUartEnsable
		printf(" [%X %X %X %X %X %X %X %X]\r\n", tx_payload.length, tx_payload.pipe, tx_payload.rssi, tx_payload.noack, tx_payload.pid, tx_payload.data[0], tx_payload.data[1], tx_payload.data[2]);
    	printf(" Send. CheckSum =  %X\r\n", Sum);
        printf(" Send OK\r\n");
    #endif	// EsbTestUartEnsable
        // Toggle one of the LEDs.
    }
    else
    {
        //	printf(" *** Sending packet failed");
    } 
}

void Action_Key1(void)
{
	PacketSend();
}

long	RxLedFlashCnt = 0;
void nrf_esb_event_handler(nrf_esb_evt_t const * p_event)
{
    switch (p_event->evt_id)
    {
        case NRF_ESB_EVENT_TX_SUCCESS:
        	PacketSendOKCnt++;
       	#ifdef	EsbTestUartEnsable
        	printf(" Change to RX\r\n");
        #endif	// EsbTestUartEnsable
            EebTxRxSwitch(RX);
            break;
        case NRF_ESB_EVENT_TX_FAILED:
            //	printf(" TX-Err\r\n");
            (void) nrf_esb_flush_tx();
            (void) nrf_esb_start_tx();
            PacketSentNGCnt++;
            tx_payload.data[3]++;
            nrf_delay_ms(2);
            PacketSend();
            break;
        case NRF_ESB_EVENT_RX_RECEIVED:
        #ifdef	EsbTestUartEnsable
            printf("RX RECEIVED EVENT\r\n");
        #endif	// EsbTestUartEnsable
            while (nrf_esb_read_rx_payload(&rx_payload) == NRF_SUCCESS)
            {
                if (rx_payload.length > 0)
                {
	            	uint8_t			Sum = 0;
            		int				i;
            		for ( i = 1 ; i < NRF_ESB_MAX_PAYLOAD_LENGTH ; i++ )
            			Sum = Sum + rx_payload.data[i];
					if ( Sum == rx_payload.data[0] )
					{
						PacketReceiveOKCnt++;
						//	printf(" I [%X]\r\n", Sum);
						if ( ++RxLedFlashCnt == 50 )
						{
							RxLedFlashCnt = 0;
							nrf_gpio_pin_toggle(GpioLed0);
						}
					}
					else
					{
						PacketReceiveNGCnt++;
                    	printf(" *** Packet NG [%x]---\r\n", Sum);
                    }
                    // Switch PTX, modify content, and send again
                    memcpy(tx_payload.data, rx_payload.data, rx_payload.length);
                    tx_payload.data[3]++;
                    nrf_delay_ms(2);
					PacketSend();
		            //	PacketSend(rx_payload.data[1]);
                }
            }
            break;
    }
}


void clocks_start( void )
{
    NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_HFCLKSTART = 1;

    while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0);
}

// ---- APP_TIMER code added here ----
APP_TIMER_DEF(m_esb_tx_timer_id);
APP_TIMER_DEF(Timer_1S_timer_id);

static void esb_send_packet_timer_callback(void *p)
{
    static nrf_esb_payload_t tx_payload = NRF_ESB_CREATE_PAYLOAD(0, 0x01, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00);
    printf("TX packet sent");
    tx_payload.noack = false;
    if (nrf_esb_write_payload(&tx_payload) == NRF_SUCCESS)
    {
        // Toggle one of the LEDs.
        nrf_gpio_pin_write(LED_1, !(tx_payload.data[1]%8>0 && tx_payload.data[1]%8<=4));
        nrf_gpio_pin_write(LED_2, !(tx_payload.data[1]%8>1 && tx_payload.data[1]%8<=5));
        nrf_gpio_pin_write(LED_3, !(tx_payload.data[1]%8>2 && tx_payload.data[1]%8<=6));
        nrf_gpio_pin_write(LED_4, !(tx_payload.data[1]%8>3));
        tx_payload.data[1]++;
    }
    else
    {
        printf("Sending packet failed");
    } 
}

extern	uint8_t		KeyDebunseTick;
void Timer_1S(void *p)
{
	static uint32_t		sPacketSendOKCnt, sPacketSentNGCnt, sPacketReceiveOKCnt, sPacketReceiveNGCnt;
	printf(" TX: %d/%d, RX: %d/%d\r\n", (PacketSendOKCnt - sPacketSendOKCnt), (PacketSentNGCnt - sPacketSentNGCnt), (PacketReceiveOKCnt - sPacketReceiveOKCnt), (PacketReceiveNGCnt - sPacketReceiveNGCnt));
	sPacketSendOKCnt = PacketSendOKCnt;
	sPacketSentNGCnt = PacketSentNGCnt;
	sPacketReceiveOKCnt = PacketReceiveOKCnt;
	sPacketReceiveNGCnt = PacketReceiveNGCnt;
}

static void timers_init(void)
{
    ret_code_t err_code;
    
    // Start the 32.768 kHz low frequency clock. Without this the app_timer module won't work
    NRF_CLOCK->TASKS_LFCLKSTART = 1;
    
    // Initialize timer module.
    err_code = app_timer_init();
    APP_ERROR_CHECK(err_code); 

    // Create timers.
    err_code = app_timer_create(&m_esb_tx_timer_id, APP_TIMER_MODE_REPEATED, esb_send_packet_timer_callback);
    APP_ERROR_CHECK(err_code);    
	err_code = app_timer_create(&Timer_1S_timer_id, APP_TIMER_MODE_REPEATED, Timer_1S); 
	APP_ERROR_CHECK(err_code);
}

static void timers_start(void)
{
    ret_code_t err_code;
#if 0
    app_timer_start(m_esb_tx_timer_id, APP_TIMER_TICKS(2000/*100*/), (void *)0);
    APP_ERROR_CHECK(err_code);
#endif
    err_code = app_timer_start(Timer_1S_timer_id, APP_TIMER_TICKS(5000/*100*/), (void *)0);
    APP_ERROR_CHECK(err_code);
}
// -----------------------------------

int main(void)
{
    uint32_t err_code;

    gpio_init();

    clocks_start();

    UART_Init();
    printf(" ... Start (RX) ...\r\n");
    timers_init();

    err_code = esb_init(RX);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_esb_start_rx();
    APP_ERROR_CHECK(err_code);

	timers_start();

    while (true)
    {
        // Nothing to do now that the app_timer runs everything, except flush the log and go to sleep
        if(NRF_LOG_PROCESS() == false)
        {
            __WFE();
        }
    }
}

The process procedure is:

1. Press a button on Host, host will send a packet (use  PacketSend() to send packet in Host.c)

2. Node will receive this packet (in line-88 of Node.c)

3. Node delay 2 ms (use nrf_delay_ms(2)), modify the packet content and send again (line-119 of Node.c)

4. Host will recerive the packet (in line-65 of Host.c)

5. Host delay 2 ms (use nrf_delay_ms(2)),  modify the packet content and send again (line-117 of Host.c)

6. Loop step 2 to 5

If I reduce the delay in step 2 and 5 to 1ms, There will cause many TX-Error in these two node

Would you please tell me how to modify this code, then I can speed-up the Packet transmit and receive?

Thank you,

Chianglin

[ovrebekk]

Hi Chianglin

How did you implement the EebTxRxSwitch(..) function?

If you are able to zip and share your projects with me it should be easier, then I can run the code on my end and see if I can reproduce the problem. 

Also, do you have a scope available so that you can analyze the ESB debug lines? 
By doing that you should be able to see when the radio of the node and host go into the different modes, which should show you where the delays are occurring. 

Best regards
Torbjørn

[chianglin]

Hi Torbjørn,

Thank you for your support.

Sorry, I don't have scope now, so I don't know the status of radio.

Please find the attach file for my full porject.

004.7z

Thank you again.

Chianglin

[ovrebekk]

Hi Chianglin

Possibly the problem is that you are using auto ACK while at the same time manually switching between PTX and PRX modes. 

When using ACK you shouldn't have to switch back and forth PTX and PRX, you can just use the ACK payload feature to send data from the PRX to the PTX if you want to. 

If for some reason you want to implement your own ACK scheme, and switch the radios between PTX and PRX, then it doesn't make sense to enable ACK's in the protocol. 

I would recommend either disabling ACK's on all your packets, or avoid switching between PTX and PRX modes by using the ACK payload feature. 

Best regards
Torbjørn 

[chianglin]

Hi Torbjørn,

You are right, I don't want to use ACK function when ESB transfer/receive all of the time.

I found there have a code which set the "noack" to faulse in line-144 of Node.c, It is my mistake.  But function "esb_send_packet_timer_callback()" will not execute, because timer "m_esb_tx_timer_id" doesn't enable.

How to modify my program to speed-up the switch between PTX and PRX, If I want to disable ACK in ESB function?

Thank you

Chianglin

[chianglin]

Hi Torbjørn,

Do you have any comment about this issue?

Thank you,

Chianglin

[ovrebekk]

Hi Chianglin

Sorry for the late reply, I have been busy with travel and other things. 

I will do a small test tomorrow and try to benchmark the TX/RX turnaround time. Once I know how fast it should be I can compare it to your results, and send you my test code. 

Best regards
Torbjørn

[ovrebekk]

Hi Chianglin

I performed some testing based on this example. 

The example is set up to do something similar to your application. It stays in RX mode most of the time, but switches briefly to TX mode when you want to send a packet, and then switches back to RX again. 

Based on the settings used in the example I measured the total turnaround from switching to TX mode, sending a packet, and switching back to RX mode, to take about 250us, plus the time needed to enable the radio in RX mode, which is 130us by default. So the total switch should happen in about 380us. 

If you change the parameters of test, such as the RF bitrate and the packet length, then this will change obviously. You can download the example and give it a try if you like. 

The next week I will be out in Easter vacation unfortunately, and won't be able to respond, but I will be back in the office on the 23rd of April. 

Best regards
Torbjørn

[chianglin]

HI Torbjørn,

Thank you for your serious support.

I will study your sample code and try to improve my TX/RX performance.

I wish you a happy holiday.

Best Regards,

Chianglin

[ovrebekk]

Hi Chianglin

Thank you for the good wishes, it was a great holiday

I hope you had some progress in the mean time. I am now back in office if you have more questions. 

Best regards
Torbjørn