31 Dec 11

Microchip’s PIC24 “F” series microcontrollers and the dsPIC33 “F” series Digital Signal Controllers which are used in the Digilent Cerebot MC7 motor controller have recently been upgraded to the PIC24 “E” and the dsPIC33 “E” series. In November, these enhanced core 16-bit “E” families have been upgraded again to include on-chip op-amps and Microchip’s Charge Time Measurement Unit peripheral (CTMU), which is used in mTouch capacitive touch-sensing user interface applications, such as keypads, buttons and sliders. The dsPIC33 and PIC24 “E” devices also offers larger memory capacity, greater I/O capability, a USB 2.0 OTG interface, and expanded motor-control, graphics, audio, and real-time embedded-control capabilities over the previous-generation of devices. These new “E” series MCUs and DSPs can support high-end industrial and commercial applications, such as multiple servo motor control, solar inverters, and running dual 3-phase motors in parallel. 

The new dsPIC33 and PIC24 “E” series feature 70 MIPS of DSP performance and an independent 6-channel Pulse Width Modulation (PWM) mode which can support multiple stepper motors and provide dead-time compensation, which reduces software overhead.  The on-chip op amps and comparators can be used in a variety of sensing applications where signal conditioning is needed, and reduce the number of external components required. This results in more efficient, smaller, and lower-cost designs, as a single DSC or MCU can be used to control the entire system.

Microchip’s dsPIC33E DSCs and PIC24E MCUs are fully compatible with the existing portfolio of dsPIC33F DSCs and PIC24H/PIC24F MCUs, software libraries and tools for easy migration. The new devices are available in many package sizes, including a small 5 mm x 5 mm 36-pin VTLA package. A new auxiliary Flash module enables designers to program or erase Flash data without slowing normal CPU operation, which is critical for motor-control, power-conversion and many other applications that require on-the-fly programming.

Microchip provides the dsPIC33E USB Starter Kit (DM330012) and PIC24E USB Starter Kit (DM240012 for the development of new applications. The dsPIC33E and PIC24E devices are also supported by Microchip’s standard development tools, including the MPLAB IDE, MPLAB ICD 3 In-Circuit Debugger, the REAL ICE In-Circuit Emulator, and the MPLAB C30 C Compiler. Additionally, several Plug-In Modules (PIMs) are available for the development kits. High-performance designs can now be created in much less with these new devices and comprehensive support packages.

30 Dec 11

The new MCP6N11 is the first instrumentation amplifier introduced from Microchip. This amplifier’s new gain setting feature by using an extra pin (VFG) differs from the traditional approach of setting gain of connecting a feedback component from the output directly to the inverting input. This new pin connects to the inverting input of the second input stage. The output voltage (VOUT) can be shifted by the voltage applied to a reference voltage pin (VREF). This pin connects to the non-inverting input of the second input stage.

This provides an improvement for many characteristics, such as gain error and drift-over temperature. This chip can be ordered in one of several minimum gain options (1, 2, 5, 10, and 100 V/V), depending on the application. Other parameters, such as input offset voltage and input noise, can be optimized with this minimum gain feature.

The MCP6N11 can operate from a single supply with a voltage range of 1.8V to 5.5V. It offers rail-to-rail input and output performance with no common mode crossover distortion on the inputs. The Common Mode Rejection Ratio (CMRR) and the Power Supply Rejection Ratio (PSRR) are both over 94 dB over the range of operation. All devices are fully specified from -40°C to +125°C.

This new instrumentation amp features Microchip’s mCal technology, which is an on-chip calibration circuit that can compensate for offset voltage changes and provides an accurate way to minimize offset drift over time and temperature. The MCP6N11 uses CMOS circuitry for low-power operation while providing a gain bandwidth product of 500 kHz, and it features a hardware shutdown pin (EN/CAL) for even more power savings. Whenever this pin is low, the part is in a low power mode and the output is high impedance.  When this pin goes high, the calibration procedure begins, and then the amplifier resumes normal operation.

These features would make the MCP6N11 ideal for many portable sensor and signal conditioning applications that use small batteries. The diagram below shows a typical application using a Wheatstone bridge (strain gage) sensor: 

28 Dec 11

R/C modelers can now experiment with new types of servo control with the new Digilent Cerebo MC7 Development Kit. Need motor control? This is a great place to start.

The basic kit includes a demonstration board that features four independent half-bridge circuits rated for 24V up to 5A. These half bridges are connected to the Motor Control PWM Module in the dsPIC microcontroller and can be configured in various ways to control two brushed DC motors, two bi-polar stepper motors, one Brushless DC motor, or one uni-polar stepper motor. The kit also includes eight RC servo motor connectors, and connections for Digilent Pmod peripheral modules. The Cerebot MC7 board is compatible with the free Microchip MPLAB® IDE and the Microchip C30 C compiler for development, programming, and debugging of the dsPIC microcontroller. A USB port is provided for programming and debugging.

Each of the four half bridges can connect to a motor with two N-FET transistors in series such that the half bridge  can either source current or sink current. A 0.01 ohm current sense resistor is connected between the source of each low side FET and ground. The voltage across this resistor is amplified and used as the feedback signal for motor control.

RC Servos generally use a pulse width modulated signal (PWM) to control the servo position. This development kit includes an advanced 8-channel motor-control PWM unit which provides eight output compare units that can be used to generate the required PWM signal for R/C servos.

The dsPIC33 DSC contains 128 KB Flash program memory and 16 KB SRAM, along with various types of serial interfaces including SPI, I2C, UART, and an enhanced CAN controller. The Cerebot MC7 board contains two push buttons and four LEDs for user I/O, and a switching 5V, 4A regulator, which enables it to operate from a single power supply.

24 Dec 11

Just released is the Texas Instruments TMP006 single-chip digital infrared MEMS temperature sensor is the first sensor or its type that can actually measure the temperature of an object without making contact with the object. These temperature sensors use a thermopile to absorb the infrared energy emitted from an object and its temperature is then calculated from the corresponding change in thermopile voltage, which is referenced to a local temperature voltage level.

The TMP006 sensor that has been optimized for thermal management and thermal protection applications, but it can be used in many other applications where remote non-contact sensing is needed, such as the temperature of the casing of an electric motor or an electronics module.

The device comes in a 1.6mm x 1.6mm package, which is about 20 times smaller than existing solutions while consuming about 10 times less power. It offers 16 bit resolution so it can detect a 0.0156 °C change in temperature over a temperature range of –40°C to +125°C. This corresponds to a sensor voltage output change that is rated at 7 μV/°C. Other notable features include an SMBus™ compatible interface, pin-programmable interface addressing, a low supply current of 240 μA, and a minimum supply voltage of  2.2 V.

22 Dec 11

We've been trying to find a way to start introducing 32 bit PIC development platforms beyond the Chipkit series - and it looks like Microchip has just made things easier for us.  Up until now, you needed to integrate a 64 or 100 pin PIC32 device, and for smaller applications, this meant a lot of wasted pins.

So Microchip has just introduced a new series of microcontrollers that would provide space and cost effective solutions for applications requiring high-quality audio, touch-sensing and graphics capabilities.

The PIC32MX1and PIC32MX2 MCUs provide 61 DMIPS of performance and are the first PIC32s to include I2S interfaces for audio processing along with Microchip’s Charge Time Measurement Unit (CTMU) peripheral for adding mTouch™ capacitive touch buttons or sensors. An 8-bit Parallel Master Port (PMP) interface is also included for graphics or external memory.

These chips are Microchip's smallest and lowest cost PIC32 microcontrollers, with packages as small as 5mm x 5mm for the 28-pin and 36-pin devices and 6mm x 6mm for the 44-pin device. The memory canbe configured with either 16/4KB or 32/8KB (Flash/SRAM).

Click for larger image

These devices also feature 1 Msps, 10-bit ADC which provides high-speed analog data acquisition on 13 channels. A Peripheral Pin Select feature enables designers to “remap” most I/O pins in the chip,making layout and design changes mush easier. A USB 2.0 interface is provided, along with other serial communications options as shown in the diagram above.

21 Dec 11

Our friends at Microchip have released a new class of microcontrollers that integrate a sub-GHz RF transmitter and an 8-bit PIC MCU with the PIC12LF1840T48A. This small 14-pin IC package (about 4.4mm square) is designed for applications such as home automation systems, remote garage door openers, remote keyless entry for cars, remotec ar starting, and many other applications where less space, lower cost, and low power-consumption is needed.

Battery life can be maximized by using an operating voltage of 1.8V. At this voltage, the operating current is only 34.5uA at 1MHz, while it goes up to about 9ma when transmitting. The standby current inthe sleep mode is about 500nA, and if the RF unit is disabled this current goes down to 30nA. It's also possible to have the power completely turned off in normal operation, so the chip would have power applied only when transmitting.

The chip features 7K of Flash program memory, 256 bytes of SRAM, and 256 bytes of data EEPROM. In-circuit serial programming and debugging can be done with two serial I/O pins. The serial interface canbe either I2C, SPI, or EUSART with auto baud rate detection. There are several modes of oscillation, with clock speeds up to 32MHz.