CCS News

Ever wanted more accuracy in the output of your PWMs? The new PIC16F1574 and PIC16F1764 family of devices both have a 16-bit PWM peripheral. The advantage of using a 16-bit PWM is that it increases the resolution of the PWM signal allowing for more precise duty cycles. Additionally each 16-bit PWM peripheral has an independent timer, this allows for generating the PWM without using one of the device's timers. The CCS C Compiler supports the new 16-bit PWM peripheral using either built-in functions or the #use pwm() library. The following is an example of how to use the #use pwm() library to setup the 16-bit PWM peripheral on a PIC16F1574:

There is a chance that you will need to read multiple analog signals at once or are the analog signals you are reading too small? The dsPIC3EPxxGS50x family of microcontrollers solve both of these problems, and the CCS C Compiler makes it easy to use. This family of chips have new ADC capable of sampling up to 5 analog inputs simultaneously. With the addition of two new functions for setting up the dedicated ADC cores, the Compiler makes it simple to read a single channel or multiple channels simultaneously. The following is an example of how to setup the ADC to read AN0 using the Dedicated ADC Core 0:

Now available are two new development boards from CCS, the Rapid-18 and LPC Starter. CCS also has updated the PIC24 development boards to now include the PIC24FJ256GA106 and the PIC24EP256GP206.

The Rapid-18 uses the PIC18F4523 and has a built-in bootloader for loading code and a USB port for text communication to the running program, and provides advanced peripherals including a 12-bit ADC. The prototyping board features a PIC18F4523 attached to a potentiometer, two pushbuttons, three LEDs, and an ICD connector.

LPC Starter is designed to be an easy way to start software testing with the low pin count (8, 14, 18 and 20) parts that are not as easy to find on other development boards. This board provides standard IC sockets for DIP parts, access to all I/O pins, three LEDs, two buttons, one potentiometer, and a USB to RS-232 converter. Dip switches are used to connect or disconnect the USB port and to select internal or external (8Mhz) clock for the 14, 18 and 20 pin sockets.

CCS has also updated the devices to newer PIC24 devices for general development. The PIC24F board has the newer PIC24F256GA106 device that includes access to 53 I/O pins. The PIC24EP board has the PIC24EP256GP206 that includes 53 I/O pins, 16 analog pins and 2 RS-232 ports.

Click here to view all CCS Development Kits: http://www.ccsinfo.com/development-kits.php

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About CCS:

CCS is a leading worldwide supplier of embedded software development tools that enable companies to develop premium products based on Microchip PIC^® MCU and dsPIC^® DSC devices. Complete proven tool chains from CCS include a code optimizing C compiler, application specific hardware platforms and software development kits. CCS' products accelerate development of energy saving industrial automation, wireless and wired communication, automotive, medical device and consumer product applications. Established in 1992, CCS is a Microchip Premier 3rd Party Partner. For more information, please visit http://www.ccsinfo.com.

PIC^® MCU, MPLAB^® IDE, MPLAB^® ICD2, MPLAB^® ICD3 and dsPIC^® are registered trademarks of Microchip Technology Inc. in the U.S. and other countries.

Support has been added to the CCS C Compiler for the new Analog-To-Digital Converter with Computation (ADC2) module that the PIC16F188xx family of devices have. In addition to legacy mode of operation the ADC2 module can be setup in Accumulate, Average, Burst Average or Low-Pass Filter modes of operation. When setup for Accumulate mode with each trigger of the ADC the conversion result is added to the accumulator and the ADCNT register is incremented. When setup for Average mode with each trigger of the ADC the conversion result is added to the accumulator and when the specified number of triggers has been done the average will be preformed on the accumulator. When setup for Burst Average mode it is similar to Average mode the difference being that when the ADC is triggered, it will perform the specified number of conversions and then perform the average calculation. When setup for Low-Pass Filter mode with each trigger of the ADC the conversion result is sent through the filter.

To support the new modes of operation the CCS C Compiler's built-in setup_adc() function has been updated to setup the ADC in these modes. Additionally an optional second and third parameter as been added to the function to set some additionally settings when using these the new modes of operation. When using Accumulate, Average or Burst Average modes the second parameter sets how much the accumulated value is divided by after each conversion. When using Low-Pass Filter mode the second parameter sets the cut-off frequency of the filter. The third parameter to the function sets the number of samples to be done before performing a threshold comparison for Average, Burst Average and Low-Pass Filter modes of operation.

In addition to the updates to the setup_adc() function the built-in functions adc_write() and adc_read() have been added to write and read some the other registers used by the ADC2 module. For example when setup for Low-Pass Filter mode the filtered result is stored in the ADFLTRH and ADFLTRL registers. After the calculation is completed the adc_read() function can be then be used to read the filtered result, for example:

Looking to store settings or data in your embedded project, but you are using a PIC^® MCU without an internal EEPROM and your design doesn't have an external EEPROM? The virtual EEPROM driver included in the CCS C Compiler adds the ability to use the PIC^® MCU's re-programmable flash memory as data storage. This driver also performs write balancing, which allows the developer to write to a specific location several times without fear of wearing out the endurance of the flash memory. The virtual EEPROM driver recently was updated to add support for PIC16 and to optimize the memory usage when used on 8-bit PIC^® MCUs (PIC16, PIC18, etc).

To add this library into your project, simply #include the file virtual_eeprom.c. The function init_virtual_eeprom() needs to be called to initialize access to the virtual EEPROM. write_virtual_eeprom() can be used to write a value to a location, and read_virtual_eeprom() can be used to read the value at a specified location. The last two erase pages of the PIC's re-programmable flash are used as storage for the virtual EEPROM system.

Here is an example of usage:

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The Capture Compare (CCP) peripheral of the PIC16 and PIC18 PIC^® MCUs and the Input Capture (IC) peripheral of the dsPIC and PIC24 PIC^® MCUs allow the MCU to capture and hold a timer value when a specific input pin reaches a user defined state. This peripheral is useful for measuring the duration between events, or determining the frequency or duty cycle of an incoming signal. This peripheral operates independent of the MCU operation, meaning it can trap the timer on the input signal without the developer having to block code execution waiting for the input signal to happen.

Version 5 of the CCS C Compiler has added a #use capture() library that makes it easy to use the CCP or IC peripheral. The API for this library provides an easy to use method for using and configuring the peripheral and timers, while also being portable from one PIC^® MCU device to another. Here is an example of its use:

The Signal Measurement Timer (SMT) is a powerful new timing peripheral found on several of the newer PIC^® MCU devices, such as the PIC16F18877 and PIC18F67K40 families. Each SMT is a 24bit timer that can operate in one of several modes:

* Timer - A simple 24bit timer, similar to the Timer0 or Timer1 peripheral.

* Gated Timer - Like timer mode above, but only increments when the signal GPIO signal is high.

* Period and duty cycle measurement - Like gated timer, increments a counter when the signal GPIO signal is high. But when the signal GPIO goes low, the timer value is stored for future use and the counter is reset back to 0.

* High and low measurement - Similar to Period and duty cycle mode above, but resets and stores on every signal edge.

* Window Measurement - akin to period and duty cycle measurement above, but measures time between two rising edge signals on the window GPIO pin.

* Gated window measurement - Like window measurement above, but time only increments when the signal GPIO pin is high.

* Time of flight - Similar to window measurement, but timing starts when the window GPIO pin goes high and the timer is stored and reset to 0 when the window GPIO pin or signal GPIO pin goes high.

* 24bit capture - Simply stores the timer value when the window GPIO pin changes state.

* 24bit counter - Counts all the rising edges of the signal GPIO pin.

* Gated counter - Comparable to the 24bit counter mode, but only increments when the window GPIO pin is high.

* Windows counter - Like the gated counter mode, but a rising edge of the window GPIO pin will store the existing timer counter and then reset it to 0.

The CCS C Compiler has been updated to add a library that allows for controlling, configuring and using the SMT in your PICmicro C projects. The functions that have been added are setup_smtX() (or setup_smt1() to setup the first SMT peripheral), smtX_status(), smtX_start(), smtX_stop(), smtX_update(), smtX_reset_timer(), smtX_read() and smtX_write(). For more help, refer to the CCS C Compiler Help file for documentation.

Here is an example of using the Timer mode to blink an LED at a 1Hz rate: