[FAQ-03]
Regarding the VCOM frequency when using EXTMODE = "L", is the following formula correct?
I understand that you invert VCOM with M1 flag,
In fact, when using it in the following cases, what is the VCOM frequency?
(FCLK is 2 MHz)
(1) One screen rewriting (eg 2.7 ", 4-bit mode, (400 x 4) x 240)
Number of bits=
(mode select + gata line + (data number x 4 bit mode)) x 240 line + data transfar =(6 + 10 + (400 x 4)) x 240 + 16 = 387, 856 bit
Frame frequency: 2 MHz x 387, 856 bit = 1 / (2 * 10 ^ 6) x 387, 856 = 0.194 s = about 5.2 Hz
Therefore, in this case the VCOM frequency is about 2.6 Hz.
(2) Area rewriting (example: 8 lines)
Number of bits=([6 + 10 + (400 x 4)) x 8 + 16 = 12,944 bit
Frame frequency = 2 MHz x 12, 944 bit = 1 / (2 * 10 ^ 6) x 12, 944 = 0.00647 s = about 154.5 Hz
Therefore, in this case the VCOM frequency is about 77.3 Hz.
Since the upper limit of the VCOM specification of the specification is 70 Hz, can not rewrite 8 Line?
answer:
The calculation formula matches the VCOM frequency when using EXTMODE = "L", but we will contact you as below.
Answer to (1):
When M1 = H, L, H, L is inserted, it is exactly it, and it is about 2.6 Hz during the rewrite period.
Answer to (2):
It is good to have it put in the specification range of the VCOM frequency specification range.
SPI-Specification 5. COM Inversion
5-1. COM polarity serial input / EXTMODE = "L as shown
ex1. M1 = H, L, H, L
ex2. M1 = H, H, L, L, H, H, L, L ... VCOM doubles the period
ex3. M1 = H, H, H, H, L, L, L, H, H, H ... 3 times
If it is a way to put it like ex3., The VCOM cycle will be about 154.5 / 3 = about 51.5 Hz.
I will post some frequently asked questions here.