UT-M 7-SEG R click

UT-M 7-SEG R click carries two SMD ultra thin LED 7-SEG displays and the MAX6969 constant-current LED driver from Maxim Integrated. The click is designed to run on either 3.3V or 5V power supply. It communicates with the target microcontroller over SPI interface.

Display features

How the click works

The 7 segment displays are interfaced to the MCU over the MAX6969 16-port, constant-current LED driver IC.

It uses the common 4-wire serial bus for communication with the MCU itself (LE, SCK, SDO, SDI on mikroBUS™ pin socket).

There is an additional OE (output enable) pin which is used to control the output driver state (enabled/disabled). Since it is the PWM output pin on the mikroBUS™ by default, the LED segments light intensity could be controlled by software too.

MAX6969 driver features

The MAX6969 uses the industry-standard, shift-register-plus-latch-type serial interface.

The driver accepts data shifted into a 16-bit shift register using data input DIN and clock input CLK. Input data appears at the DOUT output 16 clock cycles later to allow cascading of multiple MAX6969s. So, the IC allows you to connect multiple click boards™ - for applications that require more than two seven segment displays, such as digital clocks, temperature sensors, etc.

Specifications

Pinout diagram

This table shows how the pinout on UT-M 7-SEG R click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	OE	PWM control of light intensity
	NC	2	RST	INT	15	NC
Load-Enable input	LE	3	CS	TX	14	NC
Clock input	SCK	4	SCK	RX	13	NC
Serial Data Output	SDO	5	MISO	SCL	12	NC
Serial Data Input	SDI	6	MOSI	SDA	11	NC
Power supply	+3.3V	7	3.3V	5V	10	+5V	Power supply
Ground	GND	8	GND	GND	9	GND	Ground

Jumpers and settings

Programming

Code examples for UT-M 7-SEG R click, written for MikroElektronika hardware and compilers are available on Libstock.

Code snippet

The following code snippet counts down from 99 to 0 on the displays of the UT-M 7-SEG R click.

01 sbit   MAX6969_LE_PIN   at  RC2_bit;
02 sbit   MAX6969_LE_PIN_Direction   at  TRISC2_bit;
03
04 uint16_t pwmPeriod;
05 static const uint8_t minus_char = 0x40;
06
07 void systemInit()
08 {
09     AD1PCFG = 0xFFFF;
10     MAX6969_LE_PIN_Direction = 0;
11     SPI3_Init();
12     pwmPeriod = PWM_Init(5000, 1, 1, 2);
13     PWM_Start(1);
14     PWM_Set_Duty(pwmPeriod/10, 1);
15
16 }
17
18 void MAX6969_Chip_Select()
19 {
20     MAX6969_LE_PIN = 1;
21     asm nop
22     asm nop
23     asm nop
24     MAX6969_LE_PIN = 0;
25 }
26
27 static void U7SEG_Write(uint8_t number)
28 {
29     char numbers[10] = {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F};
30     uint8_t tens = number / 10;
31     uint8_t ones = number % 10;
32     if (number > 99) return;
33
34    SPI_Wr_Ptr(numbers[ones]);
35     SPI_Wr_Ptr(numbers[tens]);
36 }
37
38 void main()
39 {
40     uint8_t counter;
41
42    systemInit();
43     counter = 100;
44
45    while(counter--)
46     {
47         U7SEG_Write(counter);
48         MAX6969_Chip_Select();
49         Delay_ms(500);
50     }
51
52    SPI_Wr_Ptr(minus_char);
53     SPI_Wr_Ptr(minus_char);
54     MAX6969_Chip_Select();
55 }