DIY 2^16 encoder based on PIC

v4.2 designed by Peter JAKAB in 2004-2005
old version in December, 1999

NOTE for beginners: PICs are general purpose microcontrollers which have to be programmed before you can use them in the actual circuit! Check out this link to learn more.

This code is WORK IN PROGRESS, use at your own risk.

This encoder can transmit the state of up to 16 TTL digital inputs using an RF or infrared transmitter. When enabled, the included modulator automatically generates  the 38kHz IR carrier.

Containing a PIC microcontroller, the circuit is very flexible. You can decide which transmitter inputs will trigger a transmission. You can control the receiver outputs to be latched or momentary with the LATCH input. The Manchester-coded transmitter output is well suited for the cheapest ASK radio modules or for infrared control. Address decoding is not yet supported.

If you have trouble with programming PIC microcontrollers, you can consider builing other circuits based on Holtek HT-12D, HT-12E and Motorola MC145026, MC145027, MC145028 encoders/decoders.

2^12 encoder

pin	name	type	description
1	T0CKI	TTL input	connect to VDD
2	VDD	power	connect to power supply
3	NC	not connected
4	VSS	power	connect to ground
5	NC	not connected
6	TXOUT	TTL output	transmit output. LOW when not transmitting Connect directly to RF module DATA input pin for RF applications Connect to an IR LED directly or through a transistor for infrared applications**
7	-MOD	TTL input	modulation - on powerup pull HIGH to disable, pull LOW to enable 38kHz carrier
8	-TE	TTL input	active low enable - pull LOW to transmit
9	-TEST	TTL input	active low enable - pull LOW on powerup for generating a fixed test pattern
10	AD0	TTL input	address or data, optional active low trigger*
11	AD1	TTL input	address or data, optional active low trigger*
12	AD2	TTL input	address or data, optional active low trigger*
13	AD3	TTL input	address or data, optional active low trigger*
14	AD4	TTL input	address or data, optional active low trigger*
15	AD5	TTL input	address or data, optional active low trigger*
16	AD6	TTL input	address or data, optional active low trigger*
17	AD7	TTL input	address or data, optional active low trigger*
18	AD8	TTL input	address or data, optional active low trigger*
19	AD9	TTL input	address or data, optional active low trigger*
20	AD10	TTL input	address or data, optional active low trigger*
21	AD11	TTL input	address or data, optional active low trigger*
22	AD12	TTL input	address or data, optional active low trigger*
23	AD13	TTL input	address or data, optional active low trigger*
24	AD14	TTL input	address or data, optional active low trigger*
25	AD15	TTL input	address or data, optional active low trigger*
26	OSC2	XTAL output	oscillator crystal output
27	OSC1	XTAL input	oscillator crystal input
28	-MCLR	ST input	reset input, connect to VDD

* trigger capability is setup in the source code. Any trigger input while pulled LOW will act as the -TE input, enabling transmission
* address bits are only determined on the decoder side
** if connected directly, maximum current sourced/sunk is limited to 25 mA

Download the code for 2^16 encoder

2^12 decoder

pin	name	type	description
1	T0CKI	TTL input	connect to VDD
2	VDD	power	connect to power supply
3	NC	not connected
4	VSS	power	connect to ground
5	NC	not connected
6	RXIN	TTL input	receive input. Its polarity must match the encoder output Connect directly to RF module DATA output pin for RF applications Connect to an IR receiver IC (eg. TSOP1738) output pin directly for infrared applications
7	-INV	TTL input	active low - pull LOW to invert AD0-AD15 outputs
8	-LATCH	TTL input	active low - pull LOW to latch last received data on AD0-AD15 pull HIGH to reset AD0-AD15 to default state on no reception
9	VT	TTL output	valid transmission indicator - HIGH when a valid packet is received LOW when there is no reception
10	AD0	TTL input/output*	address input or data output*
11	AD1	TTL input/output*	address input or data output*
12	AD2	TTL input/output*	address input or data output*
13	AD3	TTL input/output*	address input or data output*
14	AD4	TTL input/output*	address input or data output*
15	AD5	TTL input/output*	address input or data output*
16	AD6	TTL input/output*	address input or data output*
17	AD7	TTL input/output*	address input or data output*
18	AD8	TTL input/output*	address input or data output*
19	AD9	TTL input/output*	address input or data output*
20	AD10	TTL input/output*	address input or data output*
21	AD11	TTL input/output*	address input or data output*
22	AD12	TTL input/output*	address input or data output*
23	AD13	TTL input/output*	address input or data output*
24	AD14	TTL input/output*	address input or data output*
25	AD15	TTL input/output*	address input or data output*
26	OSC2	XTAL output	oscillator crystal output
27	OSC1	XTAL input	oscillator crystal input
28	-MCLR	ST input	reset input, connect to VDD

* address bits are setup in software, and are fixed after programming the MCU. Others are data bits
* type is TTL input when setup as address bit, TTL output when setup as data bit

Download the code for 2^16 decoder

software

references