# interfacing with nRF24L01 chip antenna **URL:** \ **Category:** Wireless & IoT\ **Created:** [September 24, 2008, 3:55pm UTC](https://community.sparkfun.com/t/interfacing-with-nrf24l01-chip-antenna/8565 "2008-09-24T15:55:23Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![flame79boy](https://avatars.discourse-cdn.com/v4/letter/f/d26b3c/32.png) [@flame79boy](https://community.sparkfun.com/u/flame79boy)\ **Post date:** [September 24, 2008, 3:55pm UTC](https://community.sparkfun.com/t/interfacing-with-nrf24l01-chip-antenna/8565/1 "2008-09-24T15:55:23Z")
i am trying to interface PIC16F88 with nRF24L01 with chip antenna board. I am struggling to communicate with the device. Does anyone know what you have to do, to read values from nRF24L01? i am really struggling to talk to the device over SPI. Any insights would be greatly appreciated. A. ---
**Author:** ![leon\_heller](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/leon_heller/32/7602_2.png) [@leon\_heller](https://community.sparkfun.com/u/leon_heller)\ **Post date:** [September 24, 2008, 5:09pm UTC](https://community.sparkfun.com/t/interfacing-with-nrf24l01-chip-antenna/8565/2 "2008-09-24T17:09:04Z")
Here’s some code of mine: ```auto ; *************************************************************** ;Test.asm ;Tx/Rx test program for MiRF V2 ;MCU: PIC16F88 ;uses hardware 16F88 SSP module (hardware SPI) ; ;user interface ;LED - RB5, output (pin 11) ;PB - RA1, input (pin 18) ; ;nRF24L01 connections to 16F88 ; ;IRQ - RA0, input (pin 17) ;CE - RB0, output (pin 6) ;MISO/SDI - RB1, input (pin 7) ;MOSI/SDO - RB2, ouput (pin 8) ;CSN - RB3, output (pin 9) ;SCK - RB4, output (pin 10) ; *************************************************************** errorlevel -302 #define IRQ 0 #define MISO 1 #define MOSI 2 #define SCK 4 #define CSN 3 #define CE 0 #define LED 5 #define PB 1 ;defines for software SPI #define SPI_SCK 4 #define SPI_SO 2 #define SPI_SI 1 #include CBLOCK 0x20 scrA: 1 ; scratch pad 0x20 scrB: 1 count RXDATA TXDATA status data_0 data_1 data_2 data_3 data_4 ENDC org 0 nop ; ************************************************************** ;main program ; ************************************************************** call init banksel PORTB call flash_led zzz: bcf PORTB,CSN ;CSN low call short_dly movlw 0x10 ;send command (read configuration) movwf TXDATA ;put in TXDATA call spi_send_read ;send it call short_dly call spi_send_read movfw RXDATA ;status is first byte received movwf status ;save it call short_dly call spi_send_read movfw RXDATA movwf data_0 call short_dly call spi_send_read movfw RXDATA movwf data_1 call spi_send_read movfw RXDATA movwf data_2 call spi_send_read movfw RXDATA movwf data_3 call spi_send_read movfw RXDATA movwf data_4 nop bsf PORTB,CSN ;CSN high nop goto zzz stop: goto stop aaa: BANKSEL SSPSTAT LOOP: BTFSS SSPSTAT, BF ;Has data been received (transmit complete)? GOTO LOOP ;No BCF STATUS, RP0 ;Specify Bank0 MOVF SSPBUF, W ;W reg = contents of SSPBUF MOVWF RXDATA ;Save in user RAM, if data is meaningful MOVF TXDATA, W ;W reg = contents of TXDATA MOVWF SSPBUF ;New data to xmit goto aaa spi_send_read: banksel PORTB bcf PORTB,SPI_SCK ;SCK low movfw TXDATA movlw 8 ;8 bits to send movwf count sp1_1: rlf TXDATA,f ;MS bit in C btfss STATUS,C ;C = 0? goto spi_2 ;no, jump bsf PORTB,SPI_SO ;yes, output one goto spi_3 spi_2: bcf PORTB,SPI_SO ;output zero spi_3: btfsc PORTB,SPI_SI ;SPI_SI input low? goto spi_4 ;no, jump bcf STATUS,C ;yes, clear carry bit goto spi_5 spi_4: bsf STATUS,C ;set carry bit spi_5: rlf RXDATA,f ;rotate RXDATA left bsf PORTB,SPI_SCK ;SCK high to latch bit decfsz count,f ;count = 0? goto sp1_1 ;no, loop back return ;yes, return ; *************************************************************** ;initialisation ; *************************************************************** init: ;oscillator setup BANKSEL OSCCON MOVLW 0x70 ; 8 MHz int. RC osc. MOVWF OSCCON WAIT1: BTFSS OSCCON,2 ; wait until freq. is stable GOTO WAIT1 ;I/O setup BANKSEL PORTA ; select bank of PORTA CLRF PORTA ; Initialize ports by CLRF PORTB ; clearing output data latches BANKSEL ANSEL ; Select Bank of ANSEL MOVLW 0x00 ; Configure all pins MOVWF ANSEL ; as digital BANKSEL TRISB MOVLW 0x02 ; configure PORTB I/O (00000010) MOVWF TRISB MOVLW 0x01 ;configure PORTA I/O (00000001) MOVWF TRISA banksel PORTB bsf PORTB,CSN ;CSN high bcf PORTB,CE ;CE low return ;SPI setup BANKSEL SSPSTAT MOVLW 0x40 ;SPI master mode (01000000) MOVWF SSPSTAT MOVLW 0x32 ;enable SSP for SPI master mode, clock = OSC/64 (00110010) MOVWF SSPCON RETURN ; ****************************************************************** ;flash LED five times ; ****************************************************************** flash_led movlw 5 movwf count flash1: BSF PORTB,LED ;toggle LED call dly BCF PORTB,LED call dly decfsz count,f goto flash1 return ; **************************************************************** ;transmit configuration ; **************************************************************** Tx_config: banksel PORTA clrf PORTA movlw 0x38 movwf TRISA bcf PORTA,CE ;set config mode (CE = 0, CSN = 1) nop bsf PORTA,CSN call dly ;send 24 bit configuration word 001000110100111000000100 (0x234E04) MS bit first movlw 0x23 call put_byte movlw 0x4E call put_byte movlw 0x04 call put_byte call dly banksel PORTA bcf PORTA,CE nop bsf PORTA,CSN ;configuration enabled on falling edge of CSN return ; ****************************************************************** ;receive configuration ; ****************************************************************** Rx_config: banksel PORTA clrw movfw PORTA ;all bits low movlw 0x38 ;DATA1, DR1 output movfw TRISA banksel PORTA bcf PORTA,CE ;set config mode (CE = 0. CS = 1) bsf PORTA,CSN call dly ;send 24 bit configuration word 001000110100111000000101 (0x234E05) MS bit first movlw 0x23 call put_byte movlw 0x4E call put_byte movlw 0x05 call put_byte banksel PORTA bcf PORTA,CE nop bcf PORTA,CSN clrw movwf PORTA movlw 0x3A ;DATA1 muse be input movwf TRISA bcf PORTA,CE nop bsf PORTA,CSN return ; ***************************************************************************** ;transmit data ; ***************************************************************************** Tx_data: banksel PORTA bsf PORTA,CE ;power up RF front end (CE = 1) call dly movlw 0xE7 ;RF address 11100111 (0xE7) call put_byte ;clock in address movlw 0x11 ;send four data bytes (0x11223344) call put_byte movlw 0x22 call put_byte movlw 0x33 call put_byte movlw 0x44 call put_byte bcf PORTA,CE ;start transmission (CE = 0) return ; **************************************************************************** ;receive data ; **************************************************************************** Rx_data: banksel PORTA bcf PORTA,CE ;power down RF front end clrf data_0 ;zero buffers so that we can ensure that clrf data_1 ;correct date is being received clrf data_2 clrf data_3 call get_byte ;receive four bytes and save in buffer movwf data_0 call get_byte movwf data_1 call get_byte movwf data_2 call get_byte movwf data_3 bsf PORTA,CE ;power up RF front end return ; *************************************************************************** ;send byte to nRF24L01 (MS bit first) ;byte in WREG ; *************************************************************************** put_byte: banksel PORTA movwf scrA ;save byte movlw 8 ;initialise bit counter movwf count put_1: btfsc scrA,7 ;bit 7 = 0? goto put_2 ;no, jump bcf PORTA,MOSI ;clear DATA nop bsf PORTA,SCK ;clock it nop bcf PORTA,SCK goto put_3 put_2: bsf PORTA,MOSI ;set DATA nop bsf PORTA,SCK ;clock it nop bcf PORTA,SCK put_3: rlf scrA,f ;left shift for next bit decfsz count,f ;more bits? goto put_1 ;yes, loop back return ;no, return ; *************************************************************************** ;get byte from nRF24L01 (MS bit first) by clocking in data from MISO ;byte returned in WREG ; *************************************************************************** get_byte: banksel PORTA movlw 8 ;initialise bit counter movwf count get_1: btfsc PORTA,MISO ;data = 1? goto get_2 bcf scrA,0 ;no, clear MS bit goto get_3 get_2: bsf scrA,0 ;Yes, set MS bit get_3: bsf PORTA,SCK nop bcf PORTA,SCK rlf scrA,f ;left shift for next bit decfsz count,f ;more bits? goto get_1 ;no, loop back movfw scrA ;return with byte in WREG return ; ************************************************************************** ;delay routine ; ************************************************************************** dly: movlw 0xFF movwf scrB dly_1 movlw 0xFF movwf scrA dly_2: decfsz scrA, F goto dly_2 decfsz scrB,F goto dly_1 return short_dly: movlw 0x0F movwf scrA short_1: decfsz scrA, F goto dly_2 decfsz scrB,F return end ``` Leon ---
**Author:** ![flame79boy](https://avatars.discourse-cdn.com/v4/letter/f/d26b3c/32.png) [@flame79boy](https://community.sparkfun.com/u/flame79boy)\ **Post date:** [September 26, 2008, 3:46pm UTC](https://community.sparkfun.com/t/interfacing-with-nrf24l01-chip-antenna/8565/3 "2008-09-26T15:46:41Z")
hi leon, thanks for your code, it was very modular and uses software SPI routines. ---
**Author:** ![leon\_heller](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/leon_heller/32/7602_2.png) [@leon\_heller](https://community.sparkfun.com/u/leon_heller)\ **Post date:** [September 26, 2008, 4:02pm UTC](https://community.sparkfun.com/t/interfacing-with-nrf24l01-chip-antenna/8565/4 "2008-09-26T16:02:31Z")
I converted the SFE C code (it had software SPI) into assembler. I ought to update it to use hardware SPI. I’ve done that with my C code for the 18F4520 and MiRF V2. Leon