This document provides information about driving LED modules using a TLC5940 constant current LED driver and M5Stack microcontroller. It describes the hardware connections between these components and the LED modules. It also explains the software implementation for generating pulse width modulation signals to control the brightness of each LED segment with 12-bit resolution at a frequency of 2MHz updated every 16ms.

1. 5 7
2020/2/4

2. 16
5 5940
M5Stack

4. TLC5940
74HC595
TBD62783
8 Anodes for each Module
16 Cathodes of each Segment
GSCLK
BLANK
XLAT
SCLK
S-IN
S-OUT

5. LED 0 LED 1 LED 2 LED 3 LED 4 LED 5 LED 6 LED 7
16ms ( > 60Hz)
2ms
~GSCLK
BLANK = LED off
XLAT = Latch
SCLKS-IN
4096 pulse / 2ms → 2MHz
PWM data: 12bit x 16segment

7. BLANK
XLAT
SCLK
GSCLK
BLANK, XLAT: 2.048ms

8. BLANK
XLAT
SCLK
GSCLK
XLAT: 112ns
BLANK: 328ns
GSCLK: 2MHz 124ns/376ns

9. BLANK
XLAT
SCLK
GSCLK
SCLK: 8MHz 60ns/65ns

10. 32

11. LEDC Channel 0
GSCLK
2MHz0-3164MHz 25%
Divider Counter
APB_CLK
80MHz
Duty Channel
GPIO2
Frequency
(2MHz)
Resolution
(5bit)
Duty
(8/32)
LEDC Channel(0)
--> GPIO(2)
Resolution
Frequency × 2 <= APB_CLK
2MHz × 32 = 64MHz < 80MHz

12. Timer 0
2.05ms1MHz
Divider Counter
APB_CLK
80MHz
App-CPU
Divider
(80)
Alarm
(2050 count)
Interrupt
Interrupt Handler
- digitalWrite
BLANK
XLATGPIO15
GPIO12

13. Timer 0
2.05ms
App-CPU
Interrupt
Interrupt Handler
- digitalWrite
- SemaphoreGive
Non-privileged Task
- SemaphoreTake
- Make data
- Send data
Resume

14. TLC5940
GPIO5
GPIO23(MOSI)
GPIO18(SCK)
GPIO4
GPIO14
S-IN
SCLK
SS(Slave Select)
LCD

16. ハードウェア・タイマがダントツで優秀

17. 5940

18. 120
16
4096
2005.
TLC5940
Constant
Current
Driver
PWM
Control
Register
12bit
Serial
Data
Interface
16 channels LEDs
MCU
PWP
NT
GSCLK
(Gray –Scale Clock)

19. 25%
50%
75%
Pulse Cycle
Duty
OffOn
Time
Current