User's Manual

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3. Functional Description
3. Functional Description
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3.1. CPU
The ESP8285 integrates a Tensilica L106 32-bit RISC processor, which achieves extra- low
power consumption and reaches a maximum clock speed of 160 MHz. The Real-Time
Operating System (RTOS) and Wi-Fi stack allow 80% of the processing power to be
available for user application programming and development. The CPU includes the
interfaces as below:
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Programmable RAM/ROM interfaces (iBus), which can be connected with memory
controller, and can also be used to visit flash;
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Data RAM interface (dBus), which can connected with memory controller;
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AHB interface which can be used to visit the register.
Espressif !
2019.01
3.2. Memory
3.2.1. Internal SRAM and ROM
ESP8285 SoC integrates the memory controller including ROM and SRAM. MCU can
access the memory controller through iBus, dBus, and AHB interfaces. All memory units
can be accessed upon request. A memory arbiter determines the running sequence in the
arrival order of requests.
3.2.2. SPI Flash
ESP8285 has a built-in SPI flash to store user programs.
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Memory size: 1 MB
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SPI mode: Dual SPI
3.3. Crystal Oscillator
ESP-WROOM-5C uses a 26-MHz crystal oscillator. The accuracy of the crystal oscillator
should be ±10 PPM.
When using the download tool, please select the right type of crystal oscillator. In circuit
design, capacitors C1 and C2 which connect to the earth are added to the input and
output terminals of the crystal oscillator respectively. The values of the two capacitors can
be flexible, ranging from 6 pF to 22 pF, however, the specific capacitive values depend on
further testing of, and adjustment to, the overall performance of the whole circuit. Normally,
the capacitive values of C1 and C2 are within 10 pF for the 26-MHz crystal oscillator.
CONFIDENTIAL
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