Today some people call to ask questions about NRF51922 small series, and here I am grateful nice ring to support small series.
Many people find information NRF51922 online, but have not found. Why is this?
Because NRF51922 is an early test version NORDIC, it was later named NRF51422 up.
nRF51422 just to meet the needs of ultra-low-power wireless industry. This means that product developers will not need to develop separate ANT + and Bluetooth low energy products, but also can promote more smart phone manufacturers to provide built-in ANT + and Bluetooth low energy support services, and ultimately the end-user in the choice of wireless and the annex have more choice, while reducing the thorny issue compatible.
for the current Nordic (Bluetooth low Energy) and (ANT +) softDevice user, the pin-compatible hardware and similar interface shows that already have nRF51 series ANT + or Bluetooth low power Nordic customers will be consumption of products designed to keep existing hardware and firmware unchanged, adopting nRF51422 time, only for the new protocol stacks needed to support the new firmware.
The following is a small series to find the information from the official website
From the hardware point of view, is a substantially comes MCU 2.4GHz RF wireless transceiver nothing. The main special features or above in software, vendors provide a complete Bluetooth, ANT protocol handling code, which is part of pre-compiled, and user applications in different parts of the program were burned chip position, between each other through software interrupt communication. CC254X series provides source code for the user as compared to TI and compiled together in terms, this method is more simple and less error prone, substantially stack and user application programs, while running on a processor, but is substantially similar to the well river water do not make this case, whether it is learning or developing and debugging have brought very great convenience, but also to become a master SOC no wonder that the most fiery of smart wearable devices.
First, the first on the Summary:
1, the DCDC really helpful, not funny
2, power control a little dish, or light sleep, or hibernation start resets brainwashed
3, peripherals and port connections can be freely mapped, Ma Ma never have to worry I layout the matter
4, the clock system 8051feel, less linked to many brain cells
5, less variety of peripheral functions easy to use, register configuration fool, research and development of the Friends of the dog
6, timer little food, real time clock debugger uncontrollable , debugging time will pit into a dog
7, IIC static power consumption has 1mA, 1mA, 1mA! ! Do not rush off
8, peripheral temperature a little funny ....... From a distance, only the high-end
power:
and general ARM Cotex M Series MCU are similar 1.8V ~ 3.3V Jiang Zi. This is the most commonly used for CR2032 coin cell concerned can be powered directly, if using one dry cell or a rechargeable lithium battery, it is necessary to step-down the periphery of the regulator chip. The actual core chip operating voltage is 1.8V.
Special in that the DCDC chip has its own, i.e., switching regulator, a capacitor only an external inductor on it. This can greatly improve the power efficiency, electrical inch for inch gold wearable smart devices are very friendly in terms of a design. But pinch, many people probably did not notice, in fact, only the DCDC provides power to the analog portion of the on-chip, and only then turn on the radio transceivers work when digital part is still LDO, namely linear regulator. But generally speaking, this wearable device does not require much computation, most of the time the CPU is sleeping, so this did not have much impact. According to our experimental results, run Bluetooth 3.3v power supply when the peak current is not open DCDC about 13 mA, opened after almost on 9mA, the effect is obvious.
Layout Related:
Before bloggers have more time to do STM32 related development, the port pins arranged randomly assigned simply just the same. LCD displays connected Gesha, flared flash memory requires a last row of the signal line layout is simply suffering. NRF51422 very friendly and direct sequence 0-31 row over. And an analog signal such as radio frequency related, basically on one side of the crystal, on the other side of the figure, the relative layout are better processing, the image can be seen from the inside.
But by far the most important and by far the most special, is to connect peripherals and external ports can be freely mapped, and is thoroughly arbitrary mapping (except ADC), this is simply cool to fly, ah, how the board no traces are smooth, and have never wanted to use this with a sense of the other MCU ha ha ha ha.
Clock:
The MCU clock system is very simple, 8051 style, 16MHz traveled full-chip, basically do not control it. General chip configuration clock shall burn a lot of brain cells, research and development is really friendly dog ah ha ha.
Power control (PWR):
On two modes, System ON and System Off, operate the former, the latter do not work, and then switch to the latter after the former is equal to the reset system. The little dish. MCU are usually four or five different levels of low-power modes, and many continue to run the recovery from hibernation point. To achieve this effect can only remain in this System ON mode, then the CPU WFI or WFE for the CPU stopped. Datasheet above can be said to 2.4uA, but not after running the protocol stack ye are to continue to run after ..... if placed systemoff also be able to wake up, it will only save all kinds of software peripherals, CPU register contents state, and then open the data storage memory, and then enters the Off mode, after the reset is determined to restore their case, super egg pain. Fortunately, our equipment requirements are not so high, the former fixed up ~ ~ ~ the latter, it is estimated they have to hang a lot of brain cells.
Wireless transceiver (RADIO):
The wireless transceiver is still very easy to use, which can be seen embedded in a NRF24L01. Self-powered, directly connected to the peripheral connected after a 50 ohm impedance matching network of antenna to get away, how many RF basic need related development experience can achieve good performance, just want to take a good line impedance matching can be. The maximum transmit power may be provided to the software + 4dbm, we can substantially pass a few dozen m in the corridor there are duly properly.
After the general run protocol stack, the MPU protect the lives of peripherals was not visited, you do not need to control him. Do not run the protocol stack when the direct operation is also very convenient, there are some simple data transfer, or require high-throughput data transfer getting better, you can own direct operations. A wireless transceiver built a simple DMA for data transfer, the operation is very convenient.
In addition to this internal peripheral comes with a function RSSI signal strength detection, used to play Bluetooth locate what good, oh.
General purpose input output port (GPIO, GPIOTE):
Port mode is full, the pull-down, open drain, push-pull, simulation. It should be noted that if there are peripherals connected to the selected port, GPIO module basically can stop it, you do not need to configure, configuration useless. In addition to connecting peripherals and ports ADC can be easily mapped, as I said before, this so cool. Then this may be provided by the GPIO wake up the MCU, but only high and low wake, wake-up edge is not.
Then GPIOTE be extended GPIO it, there are no direct GPIO peripherals through this module can then be controlled by PPI GPIO, such as reverse, low pulled the home. Further this also allows the GPIO control these peripherals, such as high and low GPIO rising or falling edge triggered what peripherals perform certain operations. In these specific PPI tells about.
Han Han Han's inter-connected peripherals (PPI):
This chip can be considered a selling point of it, but most of that is some of the power to control the very very very very low with only equipment necessary. This stuff is probably Gesha situation pinch, the official explained that break I also read waited a long time to see to understand, in fact, fried chicken simple, listen to me talk.
Each peripheral chip has two special registers, there is only one available. They called task register (Task) and event register (Event). Task like a button, you can give it to write a control peripherals to start a task, such as ADC conversion time, a timer capture the like. Event register like a light bulb, peripherals complete a task, such as ADC to complete a conversion, GPIO to capture a falling edge on the point lights. Then squeeze, PPI is a channel, you are free to configure the source and end, like put people in here to see the lights go press the switch this feeling, in order to work in series peripherals. For example, a GPIO to capture falling on open one analog to digital converter, analog to digital conversion play triggered a reversal GPIO what what's on their own to play it.
This can play is very open, there are 32 channels, and each channel is still a task switch itself, may be comprised of numerous and complex operations.
This good is it, is to allow the CPU has more time to sleep, a lot of very simple series of continuous work is purely a mechanism to complete the internal PPI up, high speed, low power consumption. In addition, there are many short a lot of internal peripheral functions, and this principle the same, but the internal peripherals some operations in series Bale.
Analog to digital converter (the ADC):
8,9, 10-bit configuration, looks like a successive approximation, the function is relatively small, 8-channel input, a conversion can be opened, and data acquisition, and then open up interrupt. Unlike an STM32 ADC that a single continuous scan continuous dislocation that trigger the trigger to see what what a mess dazzling, this basic ran up a few lines of code. The accuracy of the words is still very good, with our Agilent 6½ most basic table + -1 alignment, error, which is one-thousandth Jiang Zi, so our products directly above it to use on-chip analog to digital converter It was converted. RF manufacturers can do to simulate sure to mention haha.
In addition to this power is also good, looks like conversion only when there is power when not in use, there is little need to turn off its power supply, it may automatically turn off the internal.
Timer (TIMER):
This is a must-MCU peripherals. However, 51422 The timer function is also relatively simple, simply, on both capture and compare functions, but also and GPIOTE used together in order to control peripheral pin, or else on their own sloshing in the film. I used TIMER almost two purposes, to generate a one Tick interrupt used to periodically trigger what what, this is generally to use the ARM core inside the timers like, this actually results 51422 neutered, is silent. It is used when the PWM generating a DAC (digital analog converter) used. This and GPIOTE can combine hardware PWM, but a lot of problems, change the PWM time must restart the timer, compare pit. And there is a very wonderful, actually the timer count register is not written to be read, all right ....... Anyway, how did seem to back this up used.
Real-time clock (RTC):
The bar that nothing special with the above difference is down but also wants to run. Also this one can read the finally count register, it is not easy. This comes Tick interrupt function, it can be neutered instead of the SysTick timer is used to run the system about her. I use this combination are generally AppTimer driver code to use them, can be a bunch of virtual software timer, very convenient.
But pinch, there are super super pit father thing, this is the clock can not be suspended debugger. So after running the protocol stack, or use the AppTimer, debugging once you start, you can not pause after once running, the program will appear magical or directly linked to the problem. The reason is simple wants, the next section talk about this talk software.
Serial port (UART):
feeling Nordic route is to take the simple to use, just as iOS and ARM ha ha. This is also true on the serial ports also function ........ remember general microcontroller or application processor, the UART is simply a universal communication port, SPI, IIC, came in the infrared have been folded, it will introduce this part of Datasheet there are almost 100 pages. The serial port settings baud rate, stop bits, get away, and then add Hair and collecting up to interrupt. But also set the baud rate so cool, do not have to go well, almost directly into the baud rate of the herd, estimated as of 8051 also benefited from the system clock because of it ha ha.
Serial Peripheral Interface (SPI / SPIS):
and the like serial port, then the host machine, the interrupt configuration for Sub sampling frequency and output edge configuration able to work, and then is Hair and collecting.
SPI slave very easy to do, but the functionality is limited. There is a simple internal DMA, roughly what you put first data, the DMA pointer refers to the past, and then select the host after the start of this part of the communication data is automatically spread out, while also saving passed in the pre-programmed position. After fixed up according to the needs a break, get away. If you need this, then the effect will be similar W25Q64 as communication certainly can not do it, but pass each other between the general chip or no problem.
IIC interface (they called TWI, two-wire interface):
This looks almost like ........ each MCU should be noted is that this static power Po Wanyi good high ah, actually there is one mA, I do not know what the problem is that chip. Anyway, I do not back immediately when turned off.
Flash Memory Controller (NVMC):
This name is a bit handsome, as always NVIC (Nested Vector Interrupt Controler, Nested Vectored Interrupt Controller), ha ha ha. Very simple use, unlock, wipe, write. However erase and write when the CPU is stuck, and therefore can not be directly used in the protocol stack run time, api interfaces are generally indirect control through the protocol stack.
A temperature sensor (the TEMP):
the Easy second only to IO controller 8051, turns on the converter, the read data, bin. And the output value is directly two binary decimal degrees Celsius. However, this measured temperature is not accurate, the difference ranging from 5-10 degrees Celsius, but the slope is not ....... 1 to bring temperature, then calibrate it yourself. Linearity is clever.