The abstract mainly introduces Analog Devices Corporation based on ARM7TDMI architecture new AD, μC702x series Micro Converter characteristic; The discussion based on ADμC702x the chip application circuit design and under the different pattern a/D converting unit’s operational factor, and showed that ADμuC702x the appraisal board provides development kit’s application method. Is for the purpose of helping reader as soon as possible familiar use ADμC702x series Micro Converter.
Key word ADμC702x Micro Converter ARM7TDMI KEIL
Introduction
ADI (Analog Devices Inc) the company is the American famous semiconductor production manufacturer, its production’s simulation component, the AD~C800 series (51 essences) the monolithic integrated circuit and the ADSP series processor in domestic had the widespread application. Recently, ADI Corporation used the new ARM7TDMI essence to design brand-new ADμC702x series MicroConverter, its operating speed might reach 45MIPS,12 the position A/D slewing rate to reach as high as 1000 ksps, was in the MicroConverter series the function strongest member. This article brief introduction ADμC702x series MicroConverter characteristic and software and hardware design.
1 ADpC702x series characteristic and hardware design
ADμC702x series MicroConverter uses the ARM7TDMI architecture, supports 16/32 simplification set of instructions (RISC), has most 16 channels, to reach as high as 1000 ksps sampling speed 12 A/D. ADμC702x the series conformity internal reference level and the temperature sensor, supported the JTAG way debugging and downloading, the external connection 32 kHz crystal oscillators, might work through the phase-locked loop under 45MHz. This serial products integration had 62 KB Flash with 8 KB SRAM, on the piece the peripheral device resources contains has UAR, SPI, double I2C serial interface, 4 timers, watch-dog, power source monitor module, 3 16 PWM outputs and programmable logic device (PLA) and so on. ADμC702x the series uses the 3V power supply, consumes the electricity under 1 MHz system clock is 3 mA,45 under the MHz clock rate consumes the electricity is 50 mA. Figure 1 is take ADμC7026 as the example system function diagram. Below introduces the AD#C702x series briefly the hardware characteristic and the related design.
1.1ADuC702x series A/D switch’s disposition and application
ADμC702x series MicroConverter contains has fast passes 12 A/D switches, may work under the 2.7~3.6V electricity voltage; When the system clock is 45 MHz, may provide 1000 ksps the sampling rates. A/D module also has the multi-channel selection switches, the differential motion sampling maintains with the piece on a/D transformation reference level (2.5 V).
ADμC702x the series A/D switch may dispose for the difference, the false difference and the single end pattern. Under the false difference and the single end pattern, the input range which A/D transforms is 0 V~VREF (reference level). Under the difference pattern, input signal’s syntype level is VCM, the input signal scope must in 0 V-AVDD (simulation power source electron), input signal’s bad mold peak-to-peak value may reach 2VREF most greatly, as shown in Figure 2. When A/D work when difference way, every two group A/D transformation pin takes a group A/D transformation channel, therefore the available A/D channel are few under this way; But the difference way can provide the very good syntype to each group simulated signal to suppress, and has the wider input range. When uses single end and the false difference way, each/D pin may take the autonomous channel work, will therefore have more A/D channels and a higher resolution (for difference way next 2 times). When design, may act according to the signal the feature selection A/D conversion mode.
1.2 ADμC702x series memory system’s characteristic and design
ADμC702x series MicroConverter has on 64 KB pieces Flash. And the peak 2 KB memory block contains has the permanent firmware, mainly uses in the factory calibration, on when the electricity internal guidance and serial port program load and so on, to user not obviously. Other 62 KB may use in the user program read-. Flash organization way for 32K×16 position. When carries out ARM (32) the set of instructions, the monocycle cannot complete takes refers to, moreover reads the data from Hash to need to insert the more extra clock cycles, therefore may map in SRAM regarding the key code section or the interrupt service to carry on. ADμC702x the series SRAM organization way for 2K×32 the position, the access speed is 2 ns, but full speed carries out the ARM code.
After system reset, the essence first carries out the 2KB internal establishment procedure, then the default takes from Flash refers. May (ADμC702x series register besides standard 37 ARM7TDMI register for memory mapping register 11 MMR) map through the REMAP register for takes from SRAM refers to, may also take from SRAM refers to the way is Flash takes through the REMAP register returns refers to the way.
ADμC702x in the series only then the multi-pin seal ADμC7026 and ADμC7027 supports the exterior memory to expand, its exterior memory main line may work under 8 or 16 band width patterns, divides into 4 memory blocks, carries on the choice through MS[3:O]. Model external bus establishment as shown in Figure 3.
1.3 ADμC702x series PLA introductions
ADμC702x series conformity programmable logic device (PLA), has contained has 2 mutual independences, but internal connection PLA module. Each module contains 8 PLA units, altogether includes 16 PLA units. Each PLA unit contains 1 double input the table look-up structure, may use in producing based on the input, no matter what serves logic output function and contains has 1 trigger. PLA unit’s structure as shown in Figure 4.
ADμC702x the series altogether has 30 to be possible to use in PLA the GPIO mouth, including 16 input ports, 14 outlets. May through dispose the GPxCON register to cause them to become PLA the exterior pin. May cause PLA through the disposition related register to become the interrupt source, starts A/D to transform or obtains in the output pin needs the signal and so on. Also includes the special design software in the AD Corporation’s development kit to use for to design the PLA register disposition.
1.4 ADμC702x power sources and other hardware related designs
Because ADμC702x the series interior conformity has the simulation and the digital two parts of electric circuits. In order to prevent the numerical part to simulate the part the disturbance, guarantees a/D precision, when power unit design wants the special attention two part of power source’s isolation. May use the double power source power supply or the single power source supplies the electromagnetism bead isolation way. Typical circuit distinction like chart 5, 6 show.
ADμC702x the series other piece on peripheral device resources, like LIART, SPI, PWM, watchdog and so on, had the widespread application in the embedded system, in ADμC702x the series use and not obvious difference, no longer gives unnecessary detail in this.
2 ADμC702x series software designs
ADμC702x series MicroConverter has used the ARM7TDMI essence, supports ARM (32) with Thumb (16) the set of instructions, contains the long multiplying order, some 5 kinds interrupt the pattern (not to define instruction, software interruption, IRQ to interrupt, the FIQ interrupt and memory visit termination), 24 interrupt sources (interrupt, timer including watch-dog to interrupt, SPI to interrupt, PLA to interrupt, A/D to interrupt, external interrupt and so on). And 5 kind of interrupt patterns are the ARM7TDMI essence altogether have. 24 interrupt sources are the basis ADμC702x series characteristic may dispose, may distinguish the disposition is the IRQ interrupt or the FIQ fast interrupt pattern. When the disposition is the FIQ pattern, will have the quicker response time. Corresponds the different working pattern, ADμC702x the series follows the ARM7TDMI essence standard, under the use different pattern register. The related ARM7TDMI essence characteristic may refer to the ARM architecture correlation data.
2.1 are suitable for ADμC702x the series compiler
ADμC702x the series is the ARM7TDMI essence, therefore may translate in principle is the ARM7TDMI set of instructions compiler may choose. ARM7TDMI is the RISC instruction nucleus, is suitable in uses the C language to develop. Now the commonly used ARM translation environment has ARM Developer Suite(ADS), RealView Developer Suite, IAR Embedded Work bench, KEILToolKit, GCC and so on. And ADS and RealView are the translation environment which ARM Corporation develops, RealView is the ADS update product. These two kind of compilers have the very high translation efficiency and the code density. IAR is a Sweden embedded system development kit and the service supplier, its different MCU compiler (for example MSP430) in domestic also has the widespread application. The KEIL C5l compiler language has the very good translation effect to 805l the nucleus C, is the domestic use broadest C5l compiler, its ARM compiler is this company’s new product. But GCC is the GNU organization designs operates the source compiler, has the different development kit collection in view of different MCU, and may the free use, but its translation efficiency not high and lacks the visualization development environment.
2.2 based on KEIL ADμC702x series programming synopsis
Because ADS in the domestic use early, already had many reference books. Presently briefly introduces ADμC702x in the development suite the KEIL compiler’s development flow. The KEII.ARM integrated development environment for μVision3, has the friendly interactive contact surface, the translation, the connection may one time complete in the integrated environment, and may carry on the software simulation or carries on downloading, the debugging through the development suite in UuNKJTAG debugger. Under the KEIL environment, but may also dispose the compiler is ADS, REALVIEW, GCC or KEIL Corporation’s ARMC compiler, therefore the KEIL environment enhanced the development flexibility enormously. The following summary under the KEIL environment, based on GCC and the KEIL compiler’s procedure development (GCC the ARM compiler may from KEIL official website free download).
When uses the KEIL environment development procedure, the user need provides assembly language outset code startup.s, the user program and the coupling configuration files. And the startup.s procedure mainly uses in installing under the interrupt entry program, the initialization different pattern the storehouse indicator and the current MCU initialization work (contains the PLL disposition and so on), after the initialization completes, staltup.s is also responsible for the vectoring procedure to C language entrance main() place. If uses GCC and the KEIL compiler, some commonly used MCU (including ADμC702x series) the startup.s code has provided by KEIL, the user may according to need to make the few revisions. Uses the KEIL bringing the compiler to be possible to complete the majority of coupling’s disposition work under the presente in figures and diagrams contact surface, does not need to compile the special document. If uses the GCC compiler also to provide the connection configuration files. Has also provided the basic connection code in view of commonly used MCU, KEIL, may from the related table of contents the copy, according to need to revise the disposition. The linked file mainly uses in various codes and the data in memory’s localization and the variable initialization.
The user program may use the C language compilation. In view of the ARM7TDMI essence’s characteristic, KEIL Corporation’s ARMC compiler CA and GCCARM compiler arm-uclibc-gcc have carried on the expansion to ANSI C, increased the key words (for example CA interrupt servicing key words _irq, absolutely memory address key words _, the GCC _attribute_ key words and so on), by facilitates the user to use the C language to program to the embedded system. When programming, the expansion key words may carry on the search through KEIL and the GCC user’s manual, may also refer to the KEIL official website the routine.
2.3 ADμC702x series procedure downloading and debugging
ADμC702x in the series JTAG connection may through development kit’s in ULINK connection to the PC USB mouth, carries on the non-invasion type under the KEIL environment (non intrusive) the debugging and carries on the programming to Flash. Is the same with other MicroConveiter series chip, ADμC702x the series may also carry on the procedure through the serial port read-in with to promote, namely SERIAL DOWN-LOADER way. This way has provided the inexpensive system upgrade plan, through when system reset or on electricity, sets at lowly the P0.O mouth, causes the system to enter SE-RIAL the DOWNLOADER pattern, through UART mouth downloading procedure to piece on F1atsh.
