LED Datasheet LED V 2.00
001-13570 Rev. *F
LED
Copyright © 2005-2014 Cypress Semiconductor Corporation. All Rights Reserved.
PSoC® Blocks
Resources
All PSoC Devices
Digital
0
API Memory (Bytes)
Analog CT
Analog SC
0
0
Flash
40
RAM
1
Pins (per
External I/O)
1
Features and Overview
Support for both Active High and Active Low circuits
Works with system shadow registers
Functions (Switch, Invert, and GetState )
The LED User Module is just a few functions to control an LED or any simple device that is controlled by
On and Off.
Figure 1.
LED Block Diagram
Functional Description
The LED User Module is a convenient way to turn a pin on and off without having to think about shadow
registers.
The project using the LED User Module which manipulates pins on a port shared with an instance of the
LED User Module must avoid direct PRTxDR writes. The Shadow Registers should be used for such
manipulation to prevent incorrect LED User Module operation.
Cypress Semiconductor Corporation
Document Number: 001-13570 Rev. *F
•
198 Champion Court
•
San Jose, CA 95134-1709
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408-943-2600
Revised April 23, 2014
LED
Placement
The LED can be placed at any I/O pin. The Drive Mode of selected pin is automatically set to the Strong
value.
Parameters and Resources
Port
Select the port where the LED will be connected.
Pin
Select pin where the LED will be connected.
Drive
The LED User Module may be configured to drive either an “Active High" or “Active Low" configuration. In an Active High configuration, the LED’s anode is connected to the PSoC pin through a resistor
and the LED’s cathode is connected to Vss. In an Active Low configuration, the LED’s cathode is
connected to the PSoC pin through a resistor and the LED’s anode is connected to Vcc.
Application Programming Interface
The Application Programming Interface (API) routines are provided as part of the user module to allow the
designer to deal with the module at a higher level. This section specifies the interface to each function
together with related constants provided by the “include" files.
Note
In this, as in all user module APIs, the values of the A and X register may be altered by calling an API
function. It is the responsibility of the calling function to preserve the values of A and X before the call if
those values are required after the call. This “registers are volatile" policy was selected for efficiency
reasons and has been in force since version 1.0 of PSoC Designer. The C compiler automatically takes
care of this requirement. Assembly language programmers must ensure their code observes the policy,
too. Though some user module API function may leave A and X unchanged, there is no guarantee they
may do so in the future.
For Large Memory Model devices, it is also the caller's responsibility to preserve any value in the
CUR_PP, IDX_PP, MVR_PP, and MVW_PP registers. Even though some of these registers may not be
modified now, there is no guarantee that will remain the case in future releases.
Here are the API programming routines provided for the LED User Module:
LED_Start, LED_Stop
Description:
Both these functions do the same thing; turn off the LED.
C Prototype:
void
void
LED_Start(void)
LED_Stop(void)
Assembler:
lcall
lcall
LED_Start
LED_Stop
Document Number: 001-13570 Rev. *F
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LED
Return Value:
None
Side Effects:
None
LED_Switch
Description:
Turns LED on or off.
C Prototype:
void
LED_Switch(BYTE bOnOff)
Assembler:
Mov a,0x01
; Turn on LED
lcall
LED_Switch
Parameters:
bOnOff: 0 = Off, Non-Zero = On
Return Values:
None
Side Effects:
None
LED_On
Description:
Turns LED on.
C Prototype:
void
LED_On(void)
Assembler:
lcall
LED_On
Parameters:
None
Return Values:
None
Side Effects:
None
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LED
LED_Off
Description:
Turns LED off.
C Prototype:
void
LED_Off(void)
Assembler:
lcall
LED_Off
Parameters:
None
Return Values:
None
Side Effects:
None
LED_Invert
Description:
Inverts the state of the LED. If the LED was on, it will be turned off; if it was off, it will be turned on.
C Prototype:
void
LED_Invert(void)
Assembler:
lcall
LED_Invert
Parameters:
None
Return Values:
None
Side Effects:
None
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LED
LED_GetState
Description:
Returns state of LED.
C Prototype:
BYTE
LED_GetState(void)
Assembler:
lcall LED_GetState
mov
[myLED_State],A
; Place result in location myLED_State
Parameters:
None
Return Value:
Returns state of LED. A zero is returned if LED if off. A 1 is returned if the LED is on. Below are some
symbolic names available in both C and ASM.
Symbolic Name
Value
LED_ON
1
LED_OFF
0
Side Effects:
None
Sample Firmware Source Code
Here is a sample project written in assembly code:
;;; Sample ASM Code for the LED User Module
;;;
;;; Turn off LED at start up then turn it on, WOW!
;;;
include "m8c.inc"
include "PSoCAPI.inc"
; part specific constants and macros
; PSoC API definitions for all User Modules
area text(ROM,REL)
export _main
_main:
mov a,0x00
call LED_Switch
mov A,0x01
call LED_Switch
; Turn Off LED
; Do user stuff
; Turn On LED
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LED
Here is a sample project written in C:
//--------------------------------------------------------// Sample C Code for the LED
// Turn LED off then, then stay in a loop and invert
// its state.
//
//
//-----------------------------------------------------------------------#include <m8c.h>
// part specific constants and macros
#include "PSoCAPI.h"
// PSoC API definitions for all User
void main(void)
{
LED_Start();
LED_Switch(1);
// Turn on LED
while(1) {
LED_Invert();
// Flash LED
}
}
Configuration Registers
None
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LED
Version History
Version
Originator
Description
1.2
DHA
Added Version History.
1.3
DHA
Enhanced pin selection to exclude used pins.
1.40
DHA
Added DRC warning message. This message appears when several LED User Modules
use the same pin.
Note
PSoC Designer 5.1 introduces a Version History in all user module datasheets. This section documents high level descriptions of the differences between the current and previous user module versions.
Document Number: 001-13570 Rev. *F
Revised April 23, 2014
Page 7 of 7
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assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.