Admin: Created page with "SPISLAVE.LIB (LBX) is a library that can be used to create a SPI slave chip when the chip does not have a hardware SPI interface. Although most AVR chips have an ISP interfac..."

2013-02-13T11:27:19Z

Created page with "SPISLAVE.LIB (LBX) is a library that can be used to create a SPI slave chip when the chip does not have a hardware SPI interface. Although most AVR chips have an ISP interfac..."

New page

SPISLAVE.LIB (LBX) is a library that can be used to create a SPI slave chip when the chip does not have a hardware SPI interface.

Although most AVR chips have an ISP interface to program the chip, the 2313 for example does not have a SPI interface.

 

When you want to control various micro’s with the SPI protocol you can use the SPISLAVE library.

 

The SPI-softslave.bas sample from the samples directory shows how you can use the SPISLAVE library.

Also look at the spi-slave.bas sample that is intended to be used with hardware SPI.

 

The sendspi.bas sample from the samples directory shows how you can use the SPI hardware interface for the master controller chip.

<source lang="bascomavr">
'-----------------------------------------------------------------------------------------
'name : spi-softslave.bas
'copyright : (c) 1995-2005, MCS Electronics
'purpose : shows how to implement a SPI SLAVE with software
'micro : AT90S2313
'suited for demo : yes
'commercial addon needed : no
'-----------------------------------------------------------------------------------------

$regfile = "2313def.dat" ' specify the used micro
$crystal = 4000000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 32 ' default use 32 for the hardware stack
$swstack = 10 ' default use 10 for the SW stack
$framesize = 40 ' default use 40 for the frame space

'Some atmel chips like the 2313 do not have a SPI port.
'The BASCOM SPI routines are all master mode routines
'This example show how to create a slave using the 2313
'ISP slave code

'define the constants used by the SPI slave
Const _softslavespi_port = Portd ' we used portD
Const _softslavespi_pin = Pind 'we use the PIND register for reading
Const _softslavespi_ddr = Ddrd ' data direction of port D

Const _softslavespi_clock = 5 'pD.5 is used for the CLOCK
Const _softslavespi_miso = 3 'pD.3 is MISO
Const _softslavespi_mosi = 4 'pd.4 is MOSI
Const _softslavespi_ss = 2 ' pd.2 is SS
'while you may choose all pins you must use the INT0 pin for the SS
'for the 2313 this is pin 2

'PD.3(7), MISO must be output
'PD.4(8), MOSI
'Pd.5(9) , Clock
'PD.2(6), SS /INT0

'define the spi slave lib
$lib "spislave.lbx"
'sepcify wich routine to use
$external _spisoftslave

'we use the int0 interrupt to detect that our slave is addressed
On Int0 Isr_sspi Nosave
'we enable the int0 interrupt
Enable Int0
'we configure the INT0 interrupt to trigger when a falling edge is detected
Config Int0 = Falling
'finally we enabled interrupts
Enable Interrupts

'
Dim _ssspdr As Byte ' this is out SPI SLAVE SPDR register
Dim _ssspif As Bit ' SPI interrupt revceive bit
Dim Bsend As Byte , I As Byte , B As Byte ' some other demo variables

_ssspdr = 0 ' we send a 0 the first time the master sends data
Do
If _ssspif = 1 Then
Print "received: " ; _ssspdr
Reset _ssspif
_ssspdr = _ssspdr + 1 ' we send this the next time
End If
Loop
</source>

When the chip has a SPI interface, you can also use the following example:

<source lang="bascomavr">
'-----------------------------------------------------------------------------------------
'name : spi-slave.bas
'copyright : (c) 1995-2005, MCS Electronics
'purpose : shows how to create a SPI SLAVE
'micro : AT90S8515
'suited for demo : yes
'commercial addon needed : no
'-----------------------------------------------------------------------------------------

$regfile = "8515def.dat" ' specify the used micro
$crystal = 3680000 ' used crystal frequency
$baud = 19200 ' use baud rate
$hwstack = 32 ' default use 32 for the hardware stack
$swstack = 10 ' default use 10 for the SW stack
$framesize = 40 ' default use 40 for the frame space

' use together with sendspi.bas
'------------------------------------------------------------------
' Tested on the STK500. The STK200 will NOT work.
' Use the STK500 or another circuit

Dim B As Byte , Rbit As Bit , Bsend As Byte

'First configure the MISO pin
Config Pinb.6 = Output ' MISO

'Then configure the SPI hardware SPCR register
Config Spi = Hard , Interrupt = On , Data Order = Msb , Master = No , Polarity = Low , Phase = 0 , Clockrate = 128

'Then init the SPI pins directly after the CONFIG SPI statement.
Spiinit

'specify the SPI interrupt
On Spi Spi_isr Nosave

'enable global interrupts
Enable Interrupts

'show that we started
Print "start"
Spdr = 0 ' start with sending 0 the first time
Do
If Rbit = 1 Then
Print "received : " ; B
Reset Rbit
Bsend = Bsend + 1 : Spdr = Bsend 'increase SPDR
End If
' your code goes here
Loop

'Interrupt routine
'since we used NOSAVE, we must save and restore the registers ourself
'when this ISR is called it will send the content from SPDR to the master
'the first time this is 0
Spi_isr:
push r24 ; save used register
in r24,sreg ; save sreg
push r24
B = Spdr
Set Rbit ' we received something
pop r24
!out sreg,r24 ; restore sreg
pop r24 ; and the used register
Return
</source> {{Languages}}

[[Category:SPI]]

SPISLAVE - Revision history

Admin: Created page with "SPISLAVE.LIB (LBX) is a library that can be used to create a SPI slave chip when the chip does not have a hardware SPI interface. Although most AVR chips have an ISP interfac..."