EFM32TG210F32 Energy Micro, EFM32TG210F32 Datasheet - Page 32

• Manufacturer Part Number: EFM32TG210F32
• Description: MCU 32BIT 32KB FLASH 32-QFN
• Manufacturer: Energy Micro
• Series: Tiny Geckor

Specifications of EFM32TG210F32

• Core Processor: ARM® Cortex-M3™
• Core Size: 32-Bit
• Speed: 32MHz
• Connectivity: EBI/EMI, I²C, IrDA, SmartCard, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, DMA, POR, PWM, WDT
• Number Of I /o: 24
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.8 V
• Data Converters: A/D 4x12b, D/A 1x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 32-VQFN Exposed Pad
• Processor Series: EFM32
• Core: ARM Cortex-M3
• Data Bus Width: 32 bit
• Data Ram Size: 32 KB
• Interface Type: UART, I2C, SPI
• Maximum Clock Frequency: 32 MHz
• Number Of Programmable I/os: 17
• Number Of Timers: 1
• Operating Supply Voltage: 1.8 V to 3.8 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Processor To Be Evaluated: EFM32TG210
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details

7.3.6 Erase and Write Operations
2010-12-21 - d0034_Rev0.90
Figure 7.2. Instruction Cache
By default, the instruction cache is automatically invalidated when the contents of the flash is changed
(i.e. written or erased). In many cases, however, the application only makes changes to data in the
flash, not code. In this case, the automatic invalidate feature can be disabled by setting AIDIS in
MSC_READCTRL. The cache can (independent of the AIDIS setting) be manually invalidated by writing
1 to INVCACHE in MSC_CMD.
In general it is highly recommended to keep the cache enabled all the time. However, for some sections
of code with very low cache hit-rate more energy-efficient execution can be achieved by disabling the
cache temporarily. To measure the hit-rate of a code-section, the built-in performance counters can
be used. Before the section, start the performance counters by writing 1 to STARTPC in MSC_CMD.
This starts the performance counters, counting from 0. At the end of the section, stop the performance
counters by writing 1 to STOPPC in MSC_CMD. The number of cache hits and cache misses for
that section can then be read from MSC_CACHEHITS and MSC_CACHEMISSES respectively. The
total number of 32-bit instruction fetches will be MSC_CACHEHITS + MSC_CACHEMISSES. Thus, the
cache hit-ratio can be calculated as MSC_CACHEHITS / (MSC_CACHEHITS + MSC_CACHEMISSES).
When MSC_CACHEHITS overflows the CHOF interrupt flag is set. When MSC_CACHEMISSES
overflows the CMOF interrupt flag is set. These flags must be cleared explicitly by software. The
range of the performance counters can thus be extended by increasing a counter in the MSC interrupt
routine. The performance counters only count when a cache lookup is performed. If the lookup fails,
MSC_CACHEMISSES is increased. If the lookup is successful, MSC_CACHEHITS is increased. For
example, a cache lookup is not performed if the cache is disabled or the code is executed from
RAM. When caching of vector fetches and instructions in interrupt routines is disabled (ICCDIS in
MSC_READCTRL is set), the performance counters do not count when these types of fetches occur
(i.e. while in interrupt context).
By default, interrupt vector fetches and instructions in interrupt routines are also cached. Some
applications may get better cache utilization by not caching instructions in interrupt context. This is done
by setting ICCDIS in MSC_READCTRL. You should only set this bit based on the results from a cache
hit ratio measurement. In general, it is recommended to keep the ICCDIS bit cleared. Note that lookups
in the cache are still performed, regardless of the ICCDIS setting - but instructions are not cached when
cache misses occur inside the interrupt routine. So, for example, if a cached function is called from the
interrupt routine, the instructions for that function will be taken from the cache.
The cache content is not retained in EM2, EM3 and EM4. The cache is therefore invalidated regardless
of the setting of AIDIS in MSC_READCTRL when entering these energy modes. Applications that switch
frequently between EM0 and EM2/3 and executes the very same non-looping code almost every time
will most likely benefit from putting this code in RAM. The interrupt vectors can also be put in RAM to
reduce current consumption even further.
The AUXHFRCO is used for timing during flash write and erase operations. To achieve correct timing,
the MSC_TIMEBASE register has to be configured according to the settings in CMU_AUXHFRCOCTRL.
BASE in MSC_TIMEBASE defines how many AUXCLK cycles - 1 there is in 1 us or 5 us, depending
on the configuration of PERIOD. To ensure that timing of flash write and erase operations is within the
specification of the flash, the value written to BASE should give at least a 10% margin with respect to
Mem ory Space
CODE
AHB-Lite Bus
IDCODE
IDCODE
MUX
AHB-Lite Bus
ICODE
Instruction Cache
Look-up Logic
Perform ance Counters
128x32
Cache
SRAM
AHB-Lite Bus
DCODE
Access
Filter
...the world's most energy friendly microcontrollers
32
AHB-Lite Bus
ICODE
Cortex-M3
www.energymicro.com