LP55231 datasheet(41/53 Pages) TI

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DIMMING

CONTROL

STEP COUNT

STEP TIME

SPAN =

187.5ms

TIME ELAPSED (ms)

375

750

1125

1500

140

141

142

143

144

145

146

147

148

RAMP INSTRUCTION

LP55231

www.ti.com

SNOSCR5 – MARCH 2013

Figure 26. Example of Ramp Instruction

SET_PWM

This instruction is used for setting the PWM value on the outputs D1 to D9 without any ramps. Set PWM output

value from 0 to 255 with PWM value bits [7:0]. Instruction execution takes sixteen 32 kHz clock cycles (=488 µs).

Name

Value (d)

Description

PWM value (i)(1)

0 - 255

PWM output duty cycle 0 - 100%

0 = local variable A

1 = local variable B

variable (ii)(1)

0 - 3

2 = global variable C

3 = register address 3CH variable D value, or register address 42H value.

(1)

(i) Valid for numerical operands. (ii) Valid for variables.

WAIT

When a wait instruction is executed, the engine is set in wait status, and the PWM values on the outputs are

frozen.

Name

Value (d)

Description

Divide master clock (32.7 kHz) by 16 which means 0.488 ms cycle time.

prescale

Divide master clock (32 768 Hz) by 512 which means 15.625 ms cycle time.

time

1 - 31

Total wait time will be = (time) x (prescale). Maximum 484 ms, minimum 0.488 ms.

LED Mapping Instructions

These instructions define the engine-to-LED mapping. The mapping information is stored in a table, which is

stored in the SRAM (program memory of the LP55231). LP55231 has three program execution engines which

can be mapped to 9 LED drivers. One engine can control one or multiple LED drivers. There are totally eleven

instructions for the engine-to-LED-driver control: mux_ld_start, mux_map_start, mux_ld_end, mux_sel, mux_clr,

mux_map_next, mux_map_prev, mux_ld_next, mux_ld_prev, mux_ld_addr and mux_map_addr.

MUX_LD_START; MUX_LD_END

Mux_ld_start and mux_ld_end define the mapping table location in the memory.

Name

Value (d)

Description

SRAM address

0-95

Mapping table start/end address

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