EPC635 datasheet(35/97 Pages) EPC

35 / 97 page

mga0

mgb0

mga1

mgb1

Int_len

Int_len_mgx1

led_mod

mga0

mgb0

mga1

mgb1

DCS0: mga0 0°, mgb0 180°

DCS0: mga1 0°, mgb1 180°

2x 160 x 30 pixel

Pixel field:

DCS 0

Figure 33: Dual MGX mode with different integration times

(upper and lower rows independently controlled by mgx0 and mgx1. One stops earlier than the other)

ADC conversion speed-up

Applications which need e.g. only 8-bit resolution e.g. grayscale mode, the frame rate can be increased further by reducing the resolution

of the ADC conversion from 12-bit default to 8, 9, 10, 11-bit optional which reduces the conversion time according Table 14.

The trade-off for 8-bit resolution (e.g. grayscale mode, setting adc_res_sel = 1 and adc_numlsb_sel = 00) is an increase of the overall

frame rate by more than 20%.

The bit-fields adc_res_sel and adc_numlsb_sel in ADC_ramp register (see chapter 8.7.22) select the ADC read-out resolution. The SIR_lo

register (0x9D) and the ISOURCE_CLK_divider (0x88) must be adjusted in parallel. Table 14 shows valid combinations to get the best per-

formance.

This mode can be combined with the 8-bit TCMI data format by setting tcmi_data_format_sel = 11 to effectively interface to an 8-bit paral -

lel interface CPU/FPGA in the application (see chapter 8.7.20).

ADC Resolution

Name

Address

8-bit

9-bit

10-bit

11-bit

12-bit

ADC_ramp

0xCD

0x1B

0x5B

0x9B

0xDB

0x13

ISOURCE_CLK_divider

0x88

0x27

0x2E

0x34

0x3A

0x3F

SIR_lo

0x9D

0x34

0x3B

0x42

0x49

0x50

Conversion time

12.25 µs

13.125 µs

14 µs

14.875µs

15.75 µs

Table 14: ADC resolution setting for signed data format (adc_skip_signmsb_en='0', default)

Skipping sign bit in grayscale mode

Grayscale mode uses single-ended readout (refer to chapter 5.7.2). However, the sign-bit is always generated as the 1st MSB. This is re-

gardless of the unsigned or two's-complement mode selected by the tcmi_data_pol bit in the TCMI_polarity register. Therefore, when 8-bit

ADC resolution is combined with 8-bit TCMI data format, sign-bit (MSB) gives out always a fixed value 1 for unsigned, 0 for two's-comple-

ment. Hence, samples are effectively generated with 7-bit resolution.

The sign bit can be skipped by setting adc_skip_signmsb_en = 1. In combination with adc_res_sel =1 and adc_numlsb_sel = 00, 8-bit ef-

fective resolution is selected. ADCs are forced to 9-bit resolution (sign-bit + 8-bit data, with a penalty of + 0.875µs conversion time) during

read-out while the sign-bit is skipped during data-out. It sends 8-bit effective data via TCMI.

Setting the adc_skip_signmsb_en =1 will yield 9-, 10-, 11-bit resolution when combined with adc_numlsb_sel = 01, 10, 11, respectively.

Table 15 shows valid combinations to get the best performance.

Characteristics subject to change without notice

35 / 97

Datasheet_epc635-V1.02

EPC635 数据表(PDF) 35 Page - Espros Photonics corp

EPC635 数据表(HTML) 35 Page - Espros Photonics corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97

数据表下载