Building the Clock Tiles

This guide is for all three Clock Tiles: Clock Generator, Clock Divider, and Clock Multiplier. They all use the same PCB with the same component values. The differences are in the pull-up / pull-down resistor and jumper placement, and the software running on the microcontroller.

The two sets of jumpers are used to configure whether the central 3.5mm socket is connected to the pot giving CV control of the pot function, or if it goes to a separate CV or gate/trigger input. Both sets of jumpers should be in the same position: either joining the top two pins (labelled “SEP. POT” on the PCB), or joining the bottom two pins. The Clock Multiplier uses no jumpers, and has the top two pins hard-wired. More on this later…

Although the PCB has a footprint for an SMD microcontroller, the DIP (on a socket) is much easier to program and reprogram. If using the SMD microcontroller programming can be done through the DIP socket, even on a fully populated PCB.

There is the choice of a power regulator in TO92 or SOT23-3 packages. Pick only one! Be sure to get the MCP1702 and not the MCP1700 — the 1700 can only handle up to 6V input.


BOM:

Qty
Value
Device
Package
Parts
Description
41kResistorR0805R1, R2, R3, R6RESISTOR
12kResistorR0805R4RESISTOR, American symbol
210kResistorR0805R5, R7RESISTOR
3100kResistorR0805R8, R9, R10RESISTOR
1B10kPotentiometer9MM SNAP-INVR19mm vertical snap-in pot, Alpha / Panasonic style with 6mm built-in knob.
1100nCapacitorC805C3Non-Polarized capacitor
21uCAPACITOR_NPOL-0805C805C1, C2Non-Polarized capacitor
1LED3MMLED1LED
11N4007DIODE-DO214ACDO214ACD4Power protection DIODE
4B54SBAT54S Schottky DiodesBAT54S_SOT23D1, D2, D3, D5Schottky barrier (double) diodes
1MCP1702-5TO92-INLINEIC3LDO Regulator PICK ONLY ONE
1MCP1702-5SOT23-3IC1LDO Regulator PICK ONLY ONE
1TILE-POWER CableFUTABA-SMALLhttp://pulplogic.com/product/tile-tail/
1ATTINY85-20DIP08U2Atmel 8-pin 2/4/8kB flash uC
1Header1X01 MaleJP2PIN HEADER
2Header1X03 MaleJP1, JP4PIN HEADER
33.5mm JackTHONKICONN3.5mm socket for Eurorack modular synthshttp://shop.erthenvar.com/collections/accessories/products/3-5mm-inline-jackshttps://www.thonk.co.uk/shop/3-5mm-jacks/
1DIP Socket8-pin
2Jumpers2.54mm

Schematics:

clocktilesschematic02 clocktilespcb02edit


Build Instructions

Clean PCB with isopropyl alcohol to remove any manufacturing residues.

Now is also a good time to file away the “mouse bites” that separate the PCB and Panel.

Solder the surface mount devices. Each of the three modules uses different configurations of input and output pull-up and pulld-own resistors. Leave the unused spots empty.

If building the Clock Multiplier, the wire jumpers can be soldered in now. Bend a bit of discarded resistor lead into a U and drop it into the holes to connect those traces. Trim the leads flush on the other side so it won’t interfere with the socket later.

 


map_7168_lznAdd the SMD-side through-hole components. The Clock Divider and Clock Generator have their jumper pins installed now.

If doing two or three different boards marking each PCB will prevent confusion later on. A white “paint pen” works best, but a black sharpie is also visible.

map_7177_lzn

 

 

Trim the IC Socket pins almost flush to the bottom of the PCB so they won’t interfere with the potentiometer (they shouldn’t anyway).

 


map_7183_lznmap_7184_lzn

Straighten the potentiometer “snap in” supports so that they can clear the DIP socket when being installed.

 

They may need to be flared outwards a wee tad.

Before soldering the pot double-check to make sure the DIP pins are contacting the metal body.

 


map_7188_lznUse the panel to help align the sockets and LED.

The power cable can be installed now.


TESTING

map_7204_lznCheck for shorts between the contacts on the power cable, and between Pin 4 and Pin 8 of the IC Socket. If there is a short, it most likely is a solder jumper between the legs of the BAT54S.

Assuming no shorts, apply power and check that Pin 8 has 5V and none of the other pins have 12V.

If testing the Clock Divider or Clock Generator, add jumpers to the two sets of jumper pins. They should both go over the same set of pins: 1 and 2, or 2 and 3. Don’t put on jumper on 1-2 and the other on 2-3. The module won’t function properly without jumpers.

Add the appropriate programmed microcontroller, and power-up the module. The led should immediately flash to signal that it has booted and loaded any EEPROM presets without error.

Test all inputs and outputs with the jumpers (if jumpered) in both positions.


CODE

Bootloader: Attiny85 16MHz internal clock

http://bitbucket.org/thx2112/clock-multiplier-tile/src

http://bitbucket.org/thx2112/clock-generator-tile/src

http://bitbucket.org/thx2112/cv-clock-divider-tile/src