XMOS XK-1A User manual

XK-1A Development Board Tutorial
IN THIS DOCUMENT
·Introduction
·Illuminate an LED
·Flash an LED
·Flash and cycle LEDs at different rates
·Run tasks concurrently
·What to read next
1 Introduction
The XK-1A is a low-cost development board based on the XMOS XS1-L1 device. It
includes a single L1, four LEDs, two press-buttons, SPI flash memory, two 16-way
IDC connectors and an XSYS debugging interface.
This tutorial shows you how to write some simple XC programs that control and
respond to the XK-1A board components. In this tutorial you learn how to:
·illuminate the LEDs
·flash the LEDs at a fixed rate
·flash the LEDs in sequence
·respond to a button press
·connect multiple boards together
2 Illuminate an LED
This part of the tutorial shows you how to illuminate an LED on your XK-1A, using
an XC port and an output statement.
2.1 Create a project
2.2 Add the application code
The program below illuminates an LED on an XK-1A.
# i nc lude < xs1 .h >
out port led = XS1_ POR T_4 F ;
Publication Date: 2012/11/8 Document Number: X7366A
XMOS © 2012, All Rights Reserved

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int m ain () {
led <: 0 b0001 ;
while (1)
;
return 0;
}
Copy and paste the code into your project, and then choose File ·Save () to save
your changes to file.
2.3 Examine the code
Take a look at the code in the editor. The declaration
out port led = XS1_PORT_4F;
declares an output port named led , which refers to the 4-bit port 4F. On the XK-1A,
the I/O pins of port 4F are connected to the LEDs labeled LED0, LED1, LED2 and
LED3.
Show image of port map..
XS1_PORT_4F[1]
LED0
LED1
LED2
LED3
BUT1
BUT2
XS1_PORT_4F[0]
XS1_PORT_4F[2]
XS1_PORT_1L
XS1_PORT_1K
XS1_PORT_4F[3]
XS1-L1
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XC input and output statements make it easy to express I/O operations on ports.
The statement
led <: 0b0001;
causes the value specified to the right of <: to be output to the port specified to
its left ( led ). The port then drives LED0 high and the other LEDs low, causing LED0
to illuminate yellow and the other LEDs to remain off.
The empty while loop prevents the program from terminating, which ensures that
the LED remains illuminated.
2.4 Build and run your project
To build and run your project, follow these steps:
1. In the Project Explorer , click your project to select it, and then choose the
menu option Project ·Build Project ( ).
The XDE displays its progress in the Console . When the build is complete, the
XDE adds the compiled binary file to the subfolder bin/Debug.
2. Choose Run ·Run Configurations.
3. In the Run Configurations dialog, in the left panel, double-click XCore Appli-
cation.
4. In the right panel, in Name, enter the name illuminate.
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5. In Project , ensure that your project is displayed. If not, click Browse to open
the Project Selection dialog, select your project, and then click OK.
6. In C/C++ Application , click Search Project to open the Program Selection
dialog, select your application binary, and then click OK.
7. In Device options , in Run on , select the option hardware , and in Target ,
ensure that the option “XMOS XTAG-2 connected to L1[0]” is selected.
If your hardware is not displayed, ensure that your XK-1A is connected to your
PC, and then click Refresh list.
8. Click Run to save your configuration and run it.
The XDE loads the binary onto your XK-1A, displaying its progress in the
Console. When the binary is loaded, the Console is cleared.
9. On your XK-1A, verify that LED0 is illuminated yellow.
10. In the Console , click the Terminate button () to stop your application running.
2.5 Exercise
To complete this part of the tutorial, perform the following steps:
1. Modify your application so that it illuminates all four LEDs.
Show a tip..
You should change the value output to the port led so that all four LEDs are
driven high.
Show a sample answer..
# i nc lude < xs1 .h >
out port led = XS1_ POR T_4 F ;
int m ain () {
led <: 0 b1111 ;
while (1)
;
return 0;
}
2. Click the Run button ( ) to reload your last Run Configuration.
The XDE determines that your source code has been updated and re-builds it,
displaying progress in the Console.
If your application contains errors, the XDE displays a dialog asking if you want
to continue launching the application. Click No , locate the first error in the
Console and double-click it to go to the offending line in the editor. When you
have fixed all errors, re-run your application.
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3. On your XK-1A, verify that all four LEDs are illuminated, and then click the
Terminate button () to stop your application running.
3 Flash an LED
This part of the tutorial shows you how to flash an LED at a fixed rate, using an XC
timer and an input statement.
3.1 Create a new project
3.2 Add the application code
The program below flashes a single LED on an XK-1A.
# i nc lude < xs1 .h >
# defin e FL ASH_ PERIO D 20 000000
out port led = XS1_ POR T_4 F ;
int main ( void ) {
time r tmr ;
unsi gne d isOn = 1;
unsi gne d t;
tmr : > t;
while (1) {
led <: isOn ;
t += FLASH_PERIOD;
tmr when t imer afte r (t ) :> void ;
isOn = !isOn;
}
return 0;
}
Copy and paste the code into your project, and then choose File ·Save () to save
your changes to file.
3.3 Examine the code
Take a look at the code in the editor. The declaration
timer tmr;
declares a variable named tmr , and allocates an available hardware timer. The L1
provides 10 timers, which can be used to determine when an event happens, or to
delay execution until a particular time. Each timer contains a 32-bit counter that is
incremented at 100MHz and whose value can be input at any time.
The statement
tmr :> t;
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inputs the value of tmr ‘s counter into the variable t . Having recorded the current
time, the statement
t += FLASH_PERIOD;
increments this value by the required delay, and the statement
tmr when timerafter(t) :> void;
delays inputting a value until the specified time is reached. The input value is not
needed, which is expressed as an input to void.
3.4 Build and run your project
To build and run your project, follow these steps:
1. In the Project Explorer , click your project to select it, and then choose the
menu option Project ·Build Project ( ).
The XDE builds your project, displaying its progress in the Console . When
the build is complete, the XDE adds the compiled binary file to the application
subfolder bin/Debug.
2. Create a new Run Configuration for your application named flash, and run it.
Show reminder..
Follow these steps:
3. Choose Run ·Run Configurations.
4. In the Run Configurations dialog, in the left panel, double-click XCore Appli-
cation.
5. In the right panel, in Name, enter the name flash.
6. In Project , ensure that your project is displayed. If not, click Browse to open
the Project Selection dialog, select your project, and then click OK.
7. As there are now two applications in your project, the XDE is unable to select
one automatically. To select, in C/C++ Application , click Search Project to
open the Program Selection dialog, select your application binary, and then
click OK.
8. In Device options , in Run on , select the option hardware , and in Target ,
ensure that the option “XMOS XTAG-2 connected to L1[0]” is selected.
If you did not stop your previous application running, your hardware may be
displayed as “XMOS XTAG-2 connected to None”.
9. Click Run to save your configuration and run it.
The XDE loads the binary onto your XK-1A, displaying its progress in the
Console. When the binary is loaded, the Console is cleared.
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10. On your XK-1A, verify that LED0 is flashing on-off, and then click the Terminate
button () to stop your application running.
3.5 Switch between projects
The Run button ( ) can be used to switch between projects. To complete this
part of the tutorial, follow these steps:
1. Click the arrow to the right of the Run button and select the Run Configuration
named illuminate.
2. On your XK-1A, verify that all four LEDs are illuminated.
3. Click the arrow to the right of the Run button and select the Run Configuration
named flash.
4. On your XK-1A, verify that LED0 is flashing on-off.
5. Modify the source of the flashing LED application to change the value of
FLASH_PERIOD from 20000000 to 40000000.
6. To build and run, just click the Run button.
The XDE launches the Run Configuration you most recently selected.
7. On your XK-1A, verify that LED0 is flashing on-off at half the rate it was flashing
previously, and then click the Terminate button () to stop your application
running.
3.6 Exercise
To complete this part of the tutorial, perform the following steps:
1. Modify your flashing LED application so that both LED0 and LED1 are flashed,
with LED0 flashed twice as fast as LED1.
Show a tip..
You should output the following pattern to the port led : 0b0011, 0b0010,
0b0011, 0b0010, 0b0001, 0b0000, 0b0001 and 0b0000.
Explain the solution in more detail..
You can define an array of integers an initialize it with the values 0b0011,
0b0010, 0b0011, 0b0010, 0b0001, 0b0000, 0b0001 and 0b0000. Then use a
loop to output this sequence of values to the port 4F.
Show a sample answer..
# i nc lude < xs1 .h >
# defi ne FL ASH_ PERIO D 20 000000
out port led = XS1_ POR T_4 F ;
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int patt ern [] = {0 b0011 ,
0b0010 ,
0b0011 ,
0b0010 ,
0b0001 ,
0b0000 ,
0b0001 ,
0 b0000 };
int main ( void ) {
time r tmr ;
unsi gne d t;
unsi gne d i = 0;
tmr : > t;
while (1) {
t += FLASH_PERIOD;
tmr when t imer afte r ( t) :> v oid ;
led <: p att ern [ i ];
i = (i +1) % 8;
}
return 0;
}
2. Run your application.
3. On your XK-1A, verify that the two LEDs are flashing at different speeds, and
then click the Terminate button () to stop your application running.
4 Flash and cycle LEDs at different rates
This part of the tutorial shows you how to flash an LED while cycling it along the
LEDs on your XK-1A.
4.1 Create an application
The program below inputs from one of two timers in a loop.
# i nc lude < xs1 .h >
# defin e FL ASH_ PERIO D 10 000000
# defin e CY CLE_ PERIO D 50 000000
out port led = XS1_ POR T_4 F ;
int main ( void ) {
timer tmrF , t mrC ;
uns igned timeF , t imeC ;
tmrF : > time F ;
tmrC : > time C ;
while (1) {
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select {
case tmrF w hen tim eraf ter ( timeF ) : > void :
/* add code to re spon d to ti meout */
break ;
case tmrC w hen t imer af te r ( timeC ) :> void :
/* add code to re spon d to ti meout */
break ;
}
}
return 0;
}
Before continuing to the next part of this tutorial, create a new project using this
code.
4.2 Examine the application code
Take a look at the application code in the editor. The first statement in main inputs
the value of the timer tmrF into the variable timeF , and the second statement
inputs the value of the timer tmrC into the variable timeC.
In the while loop, the select statement waits for the an input on either tmrF or
tmrC to become ready. It then performs the selected input and executes any code
after it up until the keyword break.
If more than one input becomes ready at the same time, only one is executed in a
single iteration of the loop; the other input is selected on the following iteration.
4.3 Exercise 1
To complete this part of the tutorial, perform the following tasks:
1. Modify the application so that:
· On each input from tmrC , the program changes which LED is flashed, cycling
between all four LEDs in sequence.
· On each input from tmrF , the program changes the state of the current LED
bewteen on and off.
Show a sample answer..
# i nc lu de < x s1 . h >
# defin e FL AS H_ PE RIOD 100 000 00
# defin e CY CL E_ PE RIOD 500 000 00
out port led = XS 1_P ORT _4F ;
in t main ( v oid ) {
unsi gne d led On = 1;
unsi gne d le dVal = 1;
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timer tmrF , t mrC ;
uns ig ne d timeF , time C ;
tmrF : > time F ;
tmrC : > time C ;
while (1) {
select {
case tmrF w hen t imer af te r ( timeF ) :> void :
ledOn = ! le dOn ;
if ( l edOn )
led <: l edVa l ;
else
led <: 0;
timeF += FL AS H_ PER IO D ;
break ;
case tmrC w hen t imer af te r ( timeC ) :> void :
ledVa l <<= 1;
if ( le dV al == 0 x10 )
ledVal = 1;
timeC += CY CL E_ PER IO D ;
break ;
}
}
return 0;
}
2. Build your project, create a new Run Configuration, and run it.
Show reminder..
Follow these steps:
3. In the Project Explorer , click your project to select it, and then choose the
menu option Project ·Build Project ( ).
If any errors are reported in the Console , double-click an error to locate it in
the editor, fix the error and then re-build your application.
4. Choose Run ·Run Configurations.
5. In the Run Configurations dialog, in the left panel, double-click XCore Appli-
cation.
6. In the right panel, in Name, enter a name for the Run Configuration.
7. In Project , ensure that your project is displayed. If not, click Browse to open
the Project Selection dialog, select your project, and then click OK.
8. In C/C++ Application , click Search Project to open the Program Selection
dialog, select your application binary, and then click OK.
9. In Device options , in Run on , select the option hardware , and in Target ,
ensure that the option “XMOS XTAG-2 connected to L1[0]” is selected.
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