MIDIbox Hardware Platform, Digital IN Module

The DIN module comes with multiple serial registers 74HC165; every register (SR) 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:

MIOS8 based applications typically allow to cascade up to 4 modules (=16 DIN SRs), makes up to 128 digital inputs
MIOS32 based applications typically allow to cascade up to 8 modules (=32 DIN SRs), makes up to 256 digital inputs

Some applications also allow to scan the shift registers in a so called "matrix" configuration. E.g. a 8x8 matrix (which is driven by a single DOUT SR and captured by a single DIN SR) can scan up to 64 buttons, a 16x16 matrix could scan up to 256 buttons. But normally 8x8 matrices are perferred due to lower latency.

Download

Note: To reduce effort only the DINX4 variant is available at Mikes PCB shop and Modular Addict's MIDIbox 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. The .pdf based schematic has been created with xcircuit. There are no special eagle schematics available, since components have been netlisted in the .brd file directly!
Module	Schematic	Layout Data (old PCB)	Quick-view (old PCB)
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
Module	Schematic	Layout Data (revised PCB)	Quick-view (revised PCB)
MBHP_DINX4_R5	mbhp_dinx4_r5.pdf	ask SmashTV	mbhp_din_r5_detail.jpg

Additional informations
File	Size	Description
mbhp_dinx4_orderlist.txt	1k	Reichelt orderlist for old layout
mbhp_dinx4_r5_orderlist.txt	1k	Reichelt orderlist for SmashTV layout
mbhp_dinx4_32buttons.pdf	16k	How to connect 32 buttons (old PCB)
mbhp_dinx4_16enc.pdf	16k	How to connect 16 rotary encoders (old PCB)
mbhp_dinx4_16enc_alps_stec16b03.pdf	16k	Same for ALPS STEC16B rotary encoders (old PCB)
mbhp_din_8x8buttons.pdf	23k	How to connect a 8x8 Button matrix (new PCB, requires also a MBHP_DOUTX4 or MBHP_DIO_MATRIX module)
mbhp_din_8x16buttons.pdf	23k	How to connect a 8x16 Button matrix (new PCB, requires also a MBHP_DOUTX4 or MBHP_DIO_MATRIX module)
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 (old PCB, only supported by MIOS8, not supported by MIOS32!)

Available Ports

Following interfaces are provided by the DINX4 module:

Name	No. of pins	Description
J1	5	Interface to CORE:J9. 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. The revised PCB layout from SmashTV uses a 2-row DIL Header instead to simplify the connection to the J8/9 connector of the core 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 the next 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. The revised PCB layout from SmashTV uses 2-row DIL headers instead so that buttons can be easily connected via 2-row DIL sockets.

Used Components

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. 8 * 5 pin DIL sockets are required for the old PCB layout, resp. 4 2x5 DIL sockets for the SmashTV layout.

Soldering Guide

This soldering guide explains how to build a DIN module based on the revised layout from SmashTV. If you want to build a DIN module based on the old layout (e.g. from Mike) please continue at this page.

	It's always a good idea to start with the smallest components to simplify mounting. So, start with the caps and resistor arrays: 8 5x10k resistor arrays (resp. discrete 36x10k resistors if you don't use resistor arrays) C1-C4: 100 nF
	Continue with the 4 IC sockets.
	Thereafter mount the 2x5 SIL headers. As you can see, we are using "polarized" headers for J1 and J2, and DIL headers for J3-J6, so that the silkscreen (which shows the pin names) won't be hidden. It's your personal choice to use "polarized" headers for these connections as well.
	Finally put the 74HC165 ICs into the sockets. Your module is now ready for use!
Two cascaded DINX4 modules connected to J8/9 of a MBHP_CORE_STM32F4 module with selfmade IDC cables.
Two cascaded DINX4 and two DOUTX4 modules connected to J8/9 of a MBHP_CORE_STM32F4 module with selfmade IDC cables. This picture gives you a more detailed view of the special (selfmade) Y cable which has one additional DIL socket at the middle so that the DIN and DOUT chain can be connected to the J8/9 connector of the core module.

Last update: 2023-11-04