MIDIbox Hardware Platform, Digital IN Module

The DIN module comes with multiple serial registers 74HC165; every register provides 8 digital inputs, which are sampled with the latch enable signal LD and shifted out with the clock signal CLK. The advantage of using such shift registers is, that they can be cascaded to a long chain without the need of more than 5 cables to the core module. The DIN board has been designed on a way which allows to cascade not only the ICs on the board, but also several DIN modules. But note that it depends on the firmware how much inputs are processed by the core module. For instance, the MIDIbox64 allows to connect up to 64 buttons = 8 ICs = 2 * DINX4, the MIDIO128 supports 128 inputs = 16 ICs = 4 DINX4 modules.

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Note: To reduce effort only the DINX4 variant is available at Mikes PCB shop. If you don't want to etch the modules by yourself, just use the DINX4 and stuff just only the ICs which are really required.

PCB data, can be viewed, modified and converted with Eagle Light Thanks to Marfurt Cyrill for layouting the DINX3 and DINX2 modules!
Module	Schematic	Layout Data	Quick-view
MBHP_DINX4_V2	mbhp_dinx4.pdf	mbhp_dinx4_v2.brd	mbhp_dinx4.gif
MBHP_DINX3_V1	similar to DINX4	mbhp_dinx3_v1.brd	mbhp_dinx3.gif
MBHP_DINX2_V1	similar to DINX4	mbhp_dinx2_v1.brd	mbhp_dinx2.gif
MBHP_DINX1_V2	mbhp_dinx1.pdf	(normaly built on veroboard)	mbhp_dinx1.jpg

Additional informations
File	Size	Description
mbhp_dinx4_orderlist.txt	1k	Reichelt orderlist
mbhp_dinx4_32buttons.pdf	16k	How to connect 32 buttons
mbhp_dinx4_mb64seq.pdf	16k	Key assigns for MIDIbox64 SEQ
mbhp_dinx4_16enc.pdf	16k	How to connect 16 rotary encoders to the MIDIbox16E (and MIOS based controllers)
mbhp_dinx4_16enc_alps_stec16b03.pdf	16k	Same for ALPS STEC16B rotary encoders
alps_stec16b03.lbr	3k	Eagle Library for Alps STEC16B03, provided by Jack (you can contact him via PM in the Forum)
mbhp_din_touchsensors.pdf	4k	connection diagram for the touch sensors

Available Ports

Following interfaces are provided by the dinx4 module:

Name	No. of pins	Description
J1	5	Interface to CORE:J9 (if buttons are used) and CORE:J6 (if encoders are used, MIDIbox16E only). DINX4:J1 provides two power pins for 5V/0V, the serial clock, the latch enable and the serial output of the register chain. This port can also be connected with J2 of another DINX module.
J2	5	Interface to another DINX4 module. DINX4:J2 provides nearly the same pins like J1, just only the serial output of the first IC is replaced by the serial input of the last IC. This port can be connected with J1 of another DINX module.
J3-J9	5	These are the digital input lines, every connector comes with 4 of them and an additional pin for ground. See mbhp_dinx4_32buttons.pdf as an example how to connect buttons to these pins, and mbhp_dinx4_16enc.pdf how to connect rotary encoders.

Used Components

Here a list of the used components. A complete orderlist for Reichelt can be found here, Mouser partlist for the US: see SmashTV's Website, if you have a orderlist for a distributor on your country, feel free publish it on this page!

Part Name	Value	Description
IC1, IC2, IC3, IC4	74HC165	The digital input shift registers
R1-R32	10k	These pull-up resistors are required if buttons are connected to the digital inputs. They ensure that the pins are supplied by defined voltage levels when a button is not closed (pressed). If you are using the DIN module with a MIDIO128, you maybe want to drive the pins "high-active" (which means: +5V = on, 0V = off). In this case please solder the two red isolated cables not to 5V, but to 0V (Vss), so that the resistors act as pull-downs. Your MIDIbox will send a lot of random MIDI traffic without these pull-ups, so don't miss them!
C1-C4	100nF	The additional bypass caps have to be placed on the bottom side of the PCB, as close to the +5V power input of the 74HC165 as possible.
R33-R36	10k	4 additional pull-up resistors. They ensure a defined level if an IC is not plugged into the socket. Your MIDIbox will send a lot of random MIDI traffic without these pull-ups, so don't miss them!
J*	*	All connectors are optional, the cables can also be soldered directly into the board. Otherwise I suggest SIL headers (header sockets), known from PC motherboards. They are cheap and usefull.
DIL	SOCKETS	Don't forget to buy sockets for the shift registers. 4 * 16 pin DIL sockets are required.

Soldering Guide

	Start with soldering the 10 bridges which save you from creating a 2-layer board. You can use the cutted legs of caps and resistors, before you throw them away after you finished all the modules! :-) Note that the 4 bridges between Pin 15 of the ICs and Vss (ground) will be soldered at the bottom side!
	This pictures shows the 4 additional bridges, realized with isolated cables.
	Stuff the other components: IC-sockets, Resistors, Connectors, ICs.
	Add also the four additional Bypass Caps between Vdd and ground (Vss) of each chip on the bottom side of the PCB as close to the +5V power input of the 74HC165 as possible. They improve the power integrity.
	This picture shows how to connect a DINX4 module to the core module (DINX4:J1 -> CORE:J9)
	A DINX4 module within a MIDIbox64.
128 inputs for MIDIO128 (yes, this pictures is a fake! ;-)

Last update: 2010-03-06