This is a simple development board for the Atmel ATtiny1634. It provides the familiar 6-pin FTDI header for connecting to serial and ISP header for programming via ISP, and it has the capacitor for auto reset. A jumper is can be used to enable or disable auto reset. It can be used with breadboard, by mounting the pins pointing down, or as a standalone board for use with female dupont jumpers, with the pins pointing up. For ease of connection w/out breadboard, four Vcc and Gnd pins are provided, instead of just one. An LDO regulator is provided for use with an external power source, or it can be powered direct from Vcc and Gnd pins. Available with and without a crystal.

Using the core available from my Github at https://github.com/SpenceKonde/ATTinyCore the ATtiny1634 can be used with the Arduino IDE, with optiboot bootloader support.

This board is sold ASSEMBLED, but WITHOUT PIN HEADER (optionally available with pin header as described below; pin header is never installed by us).

For the bare boards at a great price, see:ATTiny1634 breakout (bare board)

What sets this apart from a typical ATtiny1634 breakout board (other than the fact that they don't seem to exist) or generic SOIC-20 breakout board is that it provides the appropriate header for serial programming of an ATtiny1634, and the chip comes pre-programmed with the Optiboot bootloader, so programming it with the Arduino IDE is as simple as using an Arduino Pro Mini (You can always erase the bootloader by programming via the ISP header if you need the space and/or wish to program using Atmel Studio instead of Arduino).

The ATtiny1634 - A highly capable part

The Atmel ATtiny1634 microcontroller is one of the most capable parts in the ATtiny product line prior to the transition to the new architecture in 2016, and was one of the last "classic" ATtiny parts released. Although it doesn't have a third timer like the tiny841 does, the combination of large flash and SRAM memory, dual USART (serial), and 17 GPIO pins, on an AVR with the old style peripherals (and hence better compatibility with existing libraries) makes it a compelling package, filling a space between the smaller Tiny's, and the ever popular '328p. The second UART makes this chip particularly well suited for use with GPS, GSM, and serial WiFi adapters (like the ESP8266) without interfering with serial programming. For all boards without a crystal, the 1634R will be used - this differs only in that the internal oscillator is more tightly calibrated.

• 16k Flash, 256b EEPROM, 1k SRAM
• Optiboot bootloader support - program over serial!
• Dual hardware UARTs
• Hardware USI (for SPI or I2C master or slave)
• Hardware I2C slave
• Four PWM outputs
• 12 analog inputs
• on-chip analog comparator
• 8mhz (internal), up to 12mhz (external).

Parts required (not included):

• 1 piece 2x3 0.1" pin header, SMD or Through-hole (for ISP programming)
• 2 piece 1x13 0.1" pin header
• 1 piece 1x6 0.1" pin header, recommend 90 deg angled (for FTDI header)
• 1 piece 1x2 0.1" pin header (if using DTR reset - Not required for Rev C and later)
• 1 external power connector on 0.1" centers (optional)

Optional Colored Pin Header

An extra cost option for colored pin header kits is now available - this is standard 0.1" pitch square pin header in bright colors for an instant reminder of which pins are for which purposes (it also looks damned cool!): - 1 piece each 1x4 red and green, for Vcc and Ground pins on the two sides - 2 piece 1x9 black - 1 piece 1x6 yellow 90-degree angle, for the "FTDI" style serial header - 1 piece 2x3 white, for the ISP programming header

Optional Serial Adapter

A CH340G-based serial adapter is available as an option. This will be supplied with a 6-pin cable as shown. These are mass production adapters, however they are a cut above the most common units, and have a switch to select 3.3v or 5v operation. 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.

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

Custom options

Custom options are available for regulator and crystal - specify in order comments what regulator voltage and crystal you want. Note that at voltages above 4-4.5V, the internal oscillator runs too fast for UART communication (fig 26-64 on pg 274 of the datasheet), so the bootloader will not work and this configuration is not recommended. If you want a chip set to use the internal oscillator, and >3.3v regulator, please acknowledge that you are aware of this issue in the order comments (else I will contact you to confirm, which could delay your order). Available custom speeds are internal 1mhz or 8mhz, or external 7.3728, 8, 9.216, 11.0592, 12, 13.56, 14.318, 14.745 and 16 MHz and operating voltages of 1.8, 2.5, or 3.3v or 5v. Please refer to fig 24-1 on pg 230 of the datasheet for max rated clock speed at a given voltage - if you are requesting a crystal which is faster than the manufacturer spec for the regulator output voltage, please acknowledge in order comments that you know that you're asking for a board that is outside manufacturer spec (otherwise I will contact to confirm, delaying your order). Please allow 1-3 days extra processing time for custom order.

Optional serial adapter

These are available with an optional CH3490-based serial adapter. All of the bundled serial adapters ship with a 6-pin dupont jumper (20-30 cm, and may be mismatched if multiple serial adapters are purchased Like the basic serial adapters, they're stuck somewhere in the mail.

The "basic" version is a commercially available serial adapter with a serial adapter with a switch on it to select 5v or 3.3v operation and a full-size USB type A male connector (the kind that plugs into a computer or USB hub) (Baite BTE13). When in 3.3v mode, the TX and DTR lines still use 5v logic levels; when connected to a 3.3v boasrd, the series resistor on the TX line of the adapter, and the protection diode on the ATtiny, will work together to keep both parts operating well within manufacturer specified limits.

The Deluxe version is a board of my design - the ones shipping now were hand assembled which is why they are so expensive (I ran out of the basic ones - the deluxe ones are coming out of the ones I use daily for development); we are investigating whether we could get them made at a competitive price. The voltage switch effects both Vcc and the TX and DTR pins. Instead of an invconvenient full size USB connector, these have a common micro USB port. The power LED on the board indicates the selected voltage - Red for 5v and Blue for 3.3V. The regulator used is a high quality LDL1117-series 3.3v adapter, not a rice-grain sized piece of garbage - you should be able to have 5V come in through USB and power a 3.3V project no problem. as long as current does not exceed a half amp. This also ensures that the switch is not forced to handled excessive current. a PTC polyfuse limits current ~if~ you short power and ground. And if you think some of the features listed shouldn't be anything special - know that the reason I designed my own was that I couldn't find any for sale that didn't get at least two of these features wrong.