THE NRF24L01+ PICBASIC & PIC MICRO-CONTROLLERS
USING THE NRF24L01+ WITH A PIC MICRO-CONTROLLER
By: Don McClatchie
The NRF24L01+ is a short-range RF transceiver that operates in the 2.4GHz band with a channel bandwidth of 1 or 2 MHz. They have a practical range of about 300 feet and some with models with an added LNA can communicate over several thousand feet (Line of sight). These low-cost modules can be purchased from many sources on the internet for just a few dollars. They are frequency agile and many aspects of the transmitter and receiver operations are programmable. They are designed to be interfaced with a micro-controller and many different designs are available online. However, my search for an NRF24L01 design using a PIC micro-controller and PICBASIC software was less than fruitful. So, I set about to make one work using a PIC16F690 micro-controller and for beginners I programmed in PICBASIC. The NRF24L01 module can use what is called Enhanced Shockburst™ on individual Rx pipes so for this application the micro-controller you choose must have a built in EUSART function, I choose the PIC16F690 for my project.
The following project transmits an 8bit byte of information using Enhanced Shockburst™ from one NRF24L01 to another, the software is listed below. The program continuously loops to send the data from transmitter to receiver. You can program the unit to use other RF channels and up to five different data pipes. This software sends the same information on all 5 data pipes. It is just a sample of what can be done using these RF transceivers.
For more control see NORDIC SEMICONDUCTOR website and look up the REGISTER MAP for this IC. ™.
****************************************************************
* Name : NFR24L01T.BAS *
* Author : Don McClatchie *
* Notice : Copyright (c) 2020 *
* : All Rights Reserved *
* Date : 5/13/2020 *
* Version : 1.0 *
* Notes : Send an 8Bit Byte to an NRF24L01 Transceiver *
* : Transmitter *
****************************************************************
; PBP -p16f690
_HS_OSC ; HS Oscillator INTOSCIO
_WDT_ON ; Watchdog Timer ON
_PWRT_ON ; Power Up Timer ON
_MCLR_OFF ; INPUT PIN
_BOD_ON ; Brown Out Reset ON
_CP_ON_ALL ; Code Protect ON
_PROTECT_ON ; Code Protect ON
include “modedefs.bas” ; I/O Setup
TRISA = %00111111 ; Set All as Input
TRISB = %00010000 ; Set All Output Except Pin 13
TRISC = %01001111 ; Set All Output Except Pin 7,14,15,16,
ANSEL = %00001111 ; All Digital Except AN0,2,3,4
ANSELH = %00000000 ; All Digital (00000000)
; Defines
define OSC 4 ; Set oscillator for 4 MHz
DEFINE HSER_RCSTA 90H ; Enable Serial Port & Continuous Receive
DEFINE HSER_TXSTA 24H ; Enable USART Transmit, BRGH = 1
DEFINE HSER_BAUD 19200 ; USART BAUD Rate 19,200 TX/RX
HSEROUT [$80] ; USART Setting 128
define ADC_BITS 10 ; Setup ADC read for 10 Bits .00488V 1024
DEFINE ADC_SAMPLEUS 50
; REGISTERS
OSCCON = %01100011 ; 4MhZ,EXTFOSC2.0,HFINTNOT,LFINTYES,FOSC.2.0
ADCON0 = %10000001 ; Right Justify RA0 PIN 19 AN3
ADCON1 = %01010000 ; FOSC/16
WPUA = %00000010 ; Weak Pull Ups on Port A Pin 18
WPUB = %00000000 ; Weak Pull Ups none
OPTION_REG = %00000000 ; Weak Pull Ups Global On
TX_CE VAR PORTC.5 ; OUTPUT P-5 Chip Enable 0 = OFF 1 = ON
TX_CSN VAR PORTC.4 ; OUTPUT P-6 SPI Enable 0 = ON 1 = OFF
TX_SCK VAR PORTB.6 ; OUTPUT P-11 SPI CLOCK
TX_MOSI VAR PORTC.7 ; OUTPUT P-9 Data Input
TX_MISO VAR PORTB.4 ; INPUT P-13 Data Output
TX_IRQ VAR PORTC.3 ; INPUT P-7 IRQ Interrupt
; VARIABLES
I VAR BYTE ; Variable I
J VAR BYTE ; Variable J
DATA1 VAR BYTE ; Variable DATA1
CMD VAR BYTE ; Variable CMD for Commands Sent to Radio
LED VAR BYTE ; Variable for LEDs and Data for Transmitter
FREQSW var BYTE ; Variable for Analog Read of 8 Pos Switch
RFCHAN var byte ; Variable for RF CHANNEL
SWDATA Var BYTE ; Variable for Switch DATA 8 Bytes
SWA var word ; Variable for Switch A Analog Data
SWB var word ; Variable for Switch B Analog Data
SWC var word ; Variable for Switch C Analog Data
SWD var word ; Variable for Swtich D Analog Data
; PRESETS
PORTA = %00000000 ; Zero Port A
PORTB = %00100000 ; Zero Port B
PORTC = %00001000 ; Zero Port C
PAUSE 1000 ; Pause For Radio Start Up
PAUSE 1000 ; Pause For Radio Start Up
CLEAR
SWDATA = 128 ; This is the data to be sent (0-255) 1byte
RFCHAN = 5 ; Pre-load RF Channel 5 (0-125)
GOSUB CONFIGURE_TRANSMITTER ; Go Configure the Transmitter
MAINLOOP: ; Main Loop Transmitter
GOSUB TRANSMIT_DATA ; Jumper off Send Non-Inverted Data
GOTO MAINLOOP ; Do it again
; This sends out data
TRANSMIT_DATA: ; Transmit Data Subroutine
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $7E ; CLEAR PREVIOUS INTERUPTS $7E 01111010 W
CMD = $27 ; Load STATUS REGISTER with %001 00111
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
; PWR_UP = 1
DATA1 = $3A ; CONFIG REG DATA %00111010
CMD = $20 ; CONFIG REGISTER W CMD %001 00000
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
CMD = $E1 ; EN_AA REGISTER CLEAR TX FIFO %111 00001
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = SWDATA ; Load PAYLOAD %00110100 BYTE 1 (SWDATA)
CMD = $A0 ; Load CMD with %101 00000
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
DATA1 = SWDATA ; Load DATA1 %00111111 MORE DATA! BYTE 2
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
DATA1 = SWDATA ; Load DATA1 %00111111 MORE DATA! BYTE 3
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
DATA1 = SWDATA ; Load DATA1 %00111111 MORE DATA! BYTE 4
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CE = 1 ; PULSE CE TO START TRANSMISSION Radio On
PAUSE 10 ; Pause
TX_CE = 0 ; Clear TX_CE Chip Enable In Standby
RETURN ; Return
CONFIGURE_TRANSMITTER: ; SETS UP RF-24G FOR SHOCKBURST TRANSMISSION
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CE = 0 ; SPI Chip Select Clear Pin 15 In Standby
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $38 ; PTX, CRC ENABLE, MASK INTS 00111000 TX OFF
CMD = $20 ; Load CMD with %001 00000
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $00 ; CONFIG REGISTER AUTO RETRANSMIT OFF
CMD = $24 ; Load CMD with %001 00100
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $03 ; SETUP_AW REGISTER ADDRESS WID 5 %00000011
CMD = $23 ; SETUP_AW REGISTER Load CMD with %001 00011
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $07 ; RF_SETUP RATE 1MB, PWR 0dBM %00000111
CMD = $26 ; RF_SETUP REGISTER Load CMD with %001 00110
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = RFCHAN ; RF_CH DATA CH 00000010 RF Channel SELECT
CMD = $25 ; RF_CH RF CHANNEL CMD %001 00101
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $E7 ; SET ADDRESS E7, ALSO DEFAULT 11100111
CMD = $30 ; TX_ADDR TRANSMIT ADDRESS Load %001 10000
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
FOR J = 1 TO 5 ; For J Loop 5 Times
FOR I = 1 TO 8 ; For I Loop 8 Times DO I LOOP FIRST THEN J
TX_MOSI = DATA1.7 ; Load Bit 7 of DATA1 into TX_MOSI
TX_SCK = 1 ; SPI Clock Set
TX_SCK = 0 ; SPI Clock Clear
DATA1 = DATA1<<1 ; Shift DATA1 data Left 1 bit
NEXT I ; Do it Again
DATA1 = $E7 ; ReLoad DATA1 with %11100111 FOR 5 LOOP
NEXT J ; Do it Again
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
TX_CSN = 0 ; SPI Chip Select Clear Pin 15 SPI ON
DATA1 = $00 ; EN_AA DATA DISABLE AUTO ACK 00000000
CMD = $21 ; EN_AA REGISTER LOAD %001 00001
GOSUB TXMOSICMD ; Shift out TXMOSICMD 8 Times
GOSUB TXMOSIDATA1 ; Shift out TXMOSIDATA1 8 Times
TX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RETURN ; Return
; Channel Change Subroutine
; SUBROUTINE
TXMOSICMD: ; Shift Out MOSICMD Subroutine
FOR I = 1 TO 8 ; For I Loop 8 Times
TX_MOSI = CMD.7 ; Load TX_MOSI with CMD bit 7
TX_SCK = 1 ; SPI Clock Set
TX_SCK = 0 ; SPI Clock Clear
CMD = CMD<<1 ; Shift CMD data Left 1 bit
NEXT I ; Do it Again
RETURN ; Return
TXMOSIDATA1: ; Shift Out TXMOSIDATA1 Subroutine
FOR I = 1 TO 8 ; For I Loop 8 Times
TX_MOSI = DATA1.7 ; Load Bit 7 of DATA1 into TX_MOSI
TX_SCK = 1 ; SPI Clock Set
TX_SCK = 0 ; SPI Clock Clear
DATA1 = DATA1<<1 ; Shift DATA1 data Left 1 bit
NEXT I ; Do it Again
RETURN ; Return
END ; End
****************************************************************
* Name : NRF24L01R.BAS *
* Author : Don McClatchie *
* Notice : Copyright (c) 2020 *
* : All Rights Reserved *
* Date : 5/13/2020 *
* Version : 1.0 *
* Notes : Receiver for NRF24l01 *
* Receiver Data is found in DATA1 Variable *
****************************************************************
; PBP -p16f690
_HS_OSC ; HS Oscillator INTOSCIO
_WDT_ON ; Watchdog Timer ON
_PWRT_ON ; Power Up Timer ON
_MCLR_OFF ; INPUT PIN
_BOD_ON ; Brown Out Reset ON
_CP_ON_ALL ; Code Protect ON
_PROTECT_ON ; Code Protect ON
include “modedefs.bas” ; I/O Setup
TRISA = %00001000 ; Set All as Output Except RA3 Pin 4
TRISB = %00010000 ; Set All Output Except RB4 Pin 13
TRISC = %00001000 ; Set All Output Except RC3 Pin 7
ANSEL = %00000000 ; All Digital (00000000)
ANSELH = %00000000 ; All Digital (00000000)
; Defines
define OSC 4 ; set oscillator for 4 MHz
DEFINE HSER_RCSTA 90H ; Enable Serial Port & Continuous Receive
DEFINE HSER_TXSTA 24H ; Enable Transmit, BRGH = 1 USART
DEFINE HSER_BAUD 19200 ; USART BAUD Rate 19,200
HSEROUT [$80] ; USART Setting 128
; REGISTERS
OSCCON = %01100011 ; 4MhZ,EXTFOSC2.0,HFINTNOT,LFINTYES,FOSC.2.0
RX_CE VAR PORTC.5 ; CE OUT Pin 16 In Standby = 0 On = 1
RX_CSN VAR PORTC.4 ; CSN OUT Pin 15 SPI ON = 0 SPI OFF = 1
RX_SCK VAR PORTB.6 ; SCK OUT Pin 11 SPI CLOCK
RX_MOSI VAR PORTC.7 ; MOSI OUT Pin 9 DATA INPUT
RX_MISO VAR PORTB.4 ; MISO INPUT Pin 13 DATA OUTPUT
RX_IRQ VAR PORTC.3 ; IRQ INPUT Pin 19 INTERRUPT
; VARIABLES
I VAR BYTE ; Variable I
J VAR BYTE ; Variable J
DATA1 VAR BYTE ; Variable DATA1
CMD VAR BYTE ; Variable CMD for Commands Sent to Radio
PAYLOAD VAR BYTE ; Variable for Received Data
LED VAR BYTE ; Variable for LEDs and Data for Transmitter
AREAD var WORD ; Variable for Analog Read of 8 Pos Switch
RFCHAN var byte ; Variable for RF CHANNEL
; PRESETS
PORTA = %00000000 ; Zero Port A
PORTB = %00000000 ; Zero Port B
PORTC = %00001000 ; Zero Port C
PAYLOAD = 0
PAUSE 1000 ; Pause For Radio Start Up
PAUSE 3000 ; Pause For Radio Start Up
CLEAR
RFCHAN = 5 ; RF Channel (0-125
GOSUB CONFIGURE_RX ; Go Configure the Receiver
MAINLOOP: ; Main Loop
IF RX_IRQ = 0 THEN ; Test for Availible Data on Pin 19
GOSUB RESET_RX ; Get the data and reset the FIFO
ENDIF ; ENDIF
GOTO MAINLOOP ; Do it Again
RESET_RX: ; READ RX PAYLOAD
RX_CSN = 1 ; SPI Chip Select Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Pin 15 = 0
CMD = $61 ; EN_AA REGISTER CMD Load = %011 00001 $61
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
FOR J = 1 TO 4 ; For J Loop (PAYLOAD DATA 4 TIMES)
DATA1 = 0 ; Clear DATA1
FOR I = 1 TO 8 ; For I Loop
DATA1 = DATA1<<1 ; Shift DATA1 1 bit Left
RX_SCK = 1 ; SPI Clock Set
DATA1.0 = RX_MISO ; Load RX_MISO into DATA1 bit 0
RX_SCK = 0 ; SPI Clock Clear
NEXT I ; Do it Again
HSEROUT [#DATA1] ; SEND DATA1 TO THE HARDWARE SERIAL PORT
NEXT J ; Do it Again
HSEROUT [” “] ; Send 00000000 DATA to the Serial Port
; FLUSH RX FIFO
RX_CSN = 1 ; SPI Chip Select Pin 15 SPI OFF
CMD = $E2 ; Load CMD %11100010
RX_CSN = 0 ; SPI Chip Select Pin 15 = 0
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
RX_CSN = 1 ; SPI Chip Select Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Pin 15 = 0
; RESET INT
DATA1 = $40 ; STATUS REGISTER Load DATA1 %01000000
CMD = $27 ; STATUS REGISTER Load CMD %001 00111
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Pin 15 SPI OFF
RETURN ; Return
CONFIGURE_RX: ; SET UP FOR SHOCKBURST TRANSMISSION
RX_CSN = 1 ; SPI Chip Select set Pin 15 SPI OFF
RX_CE = 0 ; Chip Enable RX In Standby
RX_CSN = 0 ; SPI Chip Select
DATA1 = $39 ; PRX, CRC Enabled, PWR OFF %00111001
CMD = $20 ; CONFIG REGISTER CMD %001 00000 (MASKED)
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $00 ; EN_AA REGISTER ACK OFF ALL CH %00000000
CMD = $21 ; EN_AA REGISTER CMD %001 00001
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $03 ; ADDRESS WITH 5 BYTES %00000011
CMD = $23 ; SETUP_AW REGISTER CMD %001 00011
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $07 ; DATA RATE = 1 MB, PWR 1dBM %00000111
CMD = $26 ; RF_SETUP REGISTER CMD %001 00110
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $04 ; FOUR BYTE PAYLOAD %00000100
CMD = $31 ; RX_PW_PN REGISTERS CMD %001 10001
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = RFCHAN ; RF_CH REGISTER CHANNEL %00000010********
CMD = $25 ; RF_CH REGISTER CMD %00100101
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
GOSUB RXMOSIDATA1 ; Shift out RXMOSIDATA1 8 Times
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $E7 ; RX_ADDR_PO DATA 11100111 E7E7E7E7E7
CMD = $30 ; RX_ADDR_PO CMD %001 10000
GOSUB RXMOSICMD ; Shift out RXMOSICMD 8 Times
FOR J = 1 TO 5 ; For J Loop
FOR I = 1 TO 8 ; For I Loop
RX_MOSI = DATA1.7 ; Load Data1 bit 7 into RX_MOSI
RX_SCK = 1 ; SPI Clock Set
RX_SCK = 0 ; SPI Clock Clear
DATA1 = DATA1<<1 ; Shift DATA1 1 bit Left
NEXT I ; Do it Again DO I FIRST
DATA1 = $E7 ; ReLoad DATA1 %11100111 5 TIMES LOOP
NEXT J ; Do it Again DO J NEXT 5 TIMES
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CSN = 0 ; SPI Chip Select Clear
DATA1 = $3B ; PWR_UP = 1 DATA %00111011
CMD = $20 ; PWR_UP CMD %001 00000
FOR I = 1 TO 8 ; For I Loop
RX_MOSI = CMD.7 ; load RX_MOSI with bit 7 of CMD
RX_SCK = 1 ; SPI Clock Set
RX_SCK = 0 ; SPI Clock Clear
CMD = CMD<<1 ; Shift CMD 1 bit Left
NEXT I ; Do it Again
FOR I = 1 TO 8 ; For I Loop
RX_MOSI = DATA1.7 ; Load Data1 bit 7 into RX_MOSI
RX_SCK = 1 ; SPI Clock Set
RX_SCK = 0 ; SPI Clock Clear
DATA1 = DATA1<<1 ; Shift DATA1 1 bit Left
NEXT I ; Do it Again
RX_CSN = 1 ; SPI Chip Select Set Pin 15 SPI OFF
RX_CE = 1 ; Chip Enable Set Radio On
RETURN ; Return
; SUBROUTINE
RXMOSICMD: ; RXMOSI CMD SUBROUTINE
for I = 1 TO 8 ; For loop
RX_MOSI = CMD.7 ; load RX_MOSI with bit 7 of CMD
RX_SCK = 1 ; SPI Clock Set
RX_SCK = 0 ; SPI Clock Clear
CMD = CMD<<1 ; Shift CMD 1 bit Left
next I ; Do it Again
RETURN ; RETURN
RXMOSIDATA1: ; Shift Out RXMOSIDATA1 Subroutine
FOR I = 1 TO 8 ; For I Loop
RX_MOSI = DATA1.7 ; Load Data1 bit 7 into RX_MOSI
RX_SCK = 1 ; SPI Clock Set
RX_SCK = 0 ; SPI Clock Clear
DATA1 = DATA1<<1 ; Shift DATA1 1 bit Left
NEXT I ; Do it Again
RETURN ; RETURN
END ; End
