This is a simple development board for the Atmel ATtiny88 and ATTiny828. It provides an ISP header for programming via ISP as well as decoupling capacitors, a voltage regulator, and a PTC fuse protecting the external power supply from a short. For the ATtiny828, bootloader support is provided, and it can be programmed over serial via the 6-pin FTDI header; a jumper can be used to enable or disable auto reset. It can be used as a standalone board with female dupont jumpers or header, and the pins pointing up, or with breadboard (using two breadboards next to each other, as the board is too wide for a single piece of breadboard), by mounting the pins pointing down. For ease of connection without breadboard, five Vcc and Gnd pins are provided, instead of just one. These parts no not support an external crystal.

Using the ATTinyCore Universal core available from my Github at https://github.com/SpenceKonde/ATTinyCore, the ATtiny88 and 828 can be used with the Arduino IDE. The ATtiny828 supports Optiboot, which is supplied pre-loaded, allowing it to be programmed with a serial adapter (like an Arduino Pro Mini); both the ATtiny88 and ATtiny828 can be programmed with any ISP programmer (USBAsp recommended).

There are two versions of this board available - the new Rev. B version (2" x 1.65" outline) and the old version (2" x 2" outline). The old version board uses a single layout that supports the 88, 828, or an atmega328p; this made for a confusing layout, and the new versions only apply to a single family of microcontrollers - this also allowed for the board outline to be shrunk.

This board is sold ASSEMBLED, but without pins (as shown), with fuses set for 8mhz operation and - in the case of the Tiny828 - pre-loaded with the Optiboot bootloader.

Bare Board available here

ATtiny88

The ATtiny88 is a pared-down version of the popular ATmega x8 line, and as such is has a great many similarities with those popular ATmega product lines, including the fully functional on-chip SPI and I2C (while most ATtinies have either a USI, or slave-only I2C). The biggest claim to fame of the ATtiny88 is that it is very cheap in quantity, making these boards well suited to prototyping of cost-sensitive designs.

Features

• 8k Flash, 64b EEPROM, 512k SRAM
• 28 GPIO pins (27 excludi## Featuresng reset)
• Hardware SPI Master/Slave (works with normal SPI library)
• Hardware I2C Master/Slave (works with normal Wire library)
• Two PWM outputs (both on timer1, a 16-bit timer).
• 8 analog inputs
• PCINT on every pin
• on-chip analog comparator
• 8mhz (internal), up to 12mhz (external clock).
• Cheaper than the ATtiny85 or ATtiny84 in quantity.
• Assembled in the USA.

ATtiny828

The ATtiny828 has more advanced features than the ATtiny88, with the all important hardware serial port, as well as 28 different single-ended ADC channels (one on every pin!). Because of the hardware serial and hardware bootloader support, it is fully compatible with Optiboot, which fits into 512 bytes of flash on this chip, minimizing space consumed for the bootloader. All ATtiny828 boards ship with Optiboot preloaded.

Note that the internal oscillator on the 828 runs significantly faster at voltages higher than 4v, enough so that UART communication will not work without recalibrating the internal oscillator. The bootloader supplied with 5v boards compensates for this for the purposes of code upload, but this may still need to be addressed in user code. Be sure to use an appropriate voltage serial adapter for programming.

Features

• 8k Flash, 256b EEPROM, 512k SRAM
• 28 GPIO pins (27 excluding reset)
• Hardware USART
• Hardware SPI Master/Slave (works with normal SPI library)
• Hardware I2C Slave (works with SoftI2CMaster library for I2C master))
• Four PWM outputs
• 28 analog inputs (ie, every pin)
• PCINT on every pin
• on-chip analog comparator
• 8mhz (internal), up to 20mhz (external clock).
• Assembled in the USA.

Parts required (not included):

• 1 piece 2x3 0.1" pin header, SMD or Through-hole (for ISP programming)
• 2 piece 1x19 0.1" pin header
• 1 external power connector on 0.1" centers (optional)

Additional parts required for 828, for Optiboot support:

• 1 piece 1x6 0.1" pin header, recommend 90 deg angled (FTDI header)
• 1 piece 1x2 0.1" pin header (for jumper to enable reset; optional - on Rev. B boards this is hardwired and this is only necessary if this trace is cut so that auto-reset can be configured with a jumper)
• 1 piece 0.1" jumper (for above)

Optional Serial Adapter

A CH340G-based serial adapter is available as an option. This will be supplied with a 6-pin cable as shown, and the voltage of the adapter will match the voltage of the board (3.3V or 5V only). These are mass-production, no-frills commercial adapters. They break out the pins necessary for programming one of these breakout boards, or an Arduino Pro Mini or similar - Vcc, Gnd, TX, RX, DTR and CTS.

Note that the ATtiny88 does not have hardware serial support, and no bootloader for that is supplied - it must be programmed using an ISP programmer.

For a fancier CH340G adapter which breaks out all pins, check out my own CH340G-based design.