Notes on the microcontroller of TWELITE GOLD.
About Microcontrollers
The microcontroller used in TWELITE GOLD is an ARM CortexM4 core with IEEE802.15.4. TWELITE BLUE/RED use an OpenRISC core, which is a completely different microcontroller, and there are several points to note.
- While we have described content that requires special attention in terms of specifications, deeper information may be needed depending on the system and hardware requirements you are creating. For more details, please refer to the NXP JN5189 datasheet.
About the descriptions in this document
- This document mainly describes the differences from the usage with TWELITE BLUE/RED, but please refer to the JN5189 datasheet as the primary source.
- When expressing pin numbers, PIO indicates the original number of the microcontroller, while DIO/DO indicates the pin names used in TWELITE BLUE/RED. ADC1 and ADC2 are used in the same way depending on the context.
- To facilitate the porting of applications, we provide the “AHI subset” library. This library is intended for porting some of the applications we have implemented. Therefore, the behavior may differ from the API on TWELITE BLUE/RED.
Microcontroller Differences
- TWELITE BLUE/RED are big-endian, but TWELITE GOLD is little-endian.
- The ARM CortexM4 is an architecture with flexible clock configuration. As a general rule, the microcontroller’s operating clocks are 12MHz/32MHz/48MHz, and IO (such as PWM) operates at 32MHz. The main clocks for TWELITE BLUE/RED are 16MHz/32MHz, and the IO is 16MHz.
- There are restrictions on using GPIO interrupts per pin. You can use GINT (Group Interrupts) to generate an interrupt when each pin changes.
- This is implemented in the AHI subset. Since it is intended for porting our application code, it is not a comprehensive implementation, and some specifications and behaviors may differ.
- In the GINT implementation, interrupts are always generated on both edges.
- For example, if you have a pin that you want to set to a falling edge and its initial state is LOW. If the pin state transitions from LOW -> HIGH -> LOW, an interrupt will be generated for both LOW -> HIGH and HIGH -> LOW.
- While the microcontroller is running, the AHI subset suppresses the former, but when used for waking from sleep, software cannot suppress it, and it will wake up at the timing of the LOW -> HIGH transition.
- Conversely, both edges can be detected, which was not possible with TWELITE BLUE/RED, and this is also reflected in the AHI subset (
vAHI_DioInterruptEdge(),vAHI_DioWakeEdge()).
- There is a PINT function as an interrupt function for each pin. The maximum number of pins that can be used with PINT is fixed.
- This function is not used in the AHI subset and there are no special procedures for its combined use.
Microcontroller Functions
- It has a built-in RTC. While TWELITE BLUE/RED could improve timer accuracy by connecting an external oscillator, TWELITE GOLD has a built-in 32kHz oscillator and an RTC function.
- A circuit for floating-point arithmetic is not included. Calculations are performed by a software library, as before. However, the Cortex-M4 has a DSP function that uses fixed-point arithmetic, so using this is also an option.
Module Differences
- TWELITE RED/BLUE had a total of 24 pins, including 20 DIO pins, 2 dedicated SPI pins, and 2 dedicated analog pins. In contrast, TWELITE GOLD has 22 pins: 16 dedicated digital pins and 6 shared digital-analog pins. This means that two pins are shared on TWELITE GOLD.
- PIO0 is shared with DO0 (SPICLK) and DIO11.
- PIO14 is shared with ADC2 (Vref) and DIO8.
- In the AHI subset, you must set DIO8 to a digital port before using it.
- While the DIO pins on TWELITE BLUE/RED were in a high-impedance, pull-up state at reset, the state of each pin on TWELITE GOLD is different. In the AHI subset, DIO0..19 and DO0,1 are set as input and pull-up at initialization, while ADC1,2 are set as analog inputs.
Pins that require careful handling
For details, refer to the JN518x datasheet.
- PIO=5 (ISP_ENTRY): Similar to TWELITE BLUE/RED, when this pin is in a LOW state at reset, it enters a mode for firmware writing, etc.
- PIO=4 (ISE_SEL): When ISP_ENTRY is enabled, the subsequent behavior is changed. If it is not set to a HIGH level during firmware writing, firmware cannot be written.
- PIO=10, 11: These are mainly intended for I2C use, so they differ from other pins that can be used for GPIO. Specifically, there is no pull-up/down setting.
About Peripherals
Please refer to the documentation for the TWENETmwf (which organizes major functions through peripheral procedures) and TWENETcmpt libraries (intended for porting code using AHI).