S13131.h File Reference

#include <stdint.h>
#include <ReadWriteBits.h>

Go to the source code of this file.

Macros
#define	MAX_NUM_PIXELS   512
	S13131-512 has 512 pixels.

Typedefs
typedef uint8_t volatile *const	s13131_ptr
typedef uint8_t const	s13131_pin
typedef uint8_t const	s13131_bit

Functions
uint8_t	MSB (uint16_t msb_lsb)
uint8_t	LSB (uint16_t msb_lsb)
void	S13131PinSetup (void)
void	S13131StartClocking (void)
void	WaitForS13131ClkLow (void)
void	WaitForS13131ClkHigh (void)
void	S13131Expose (void)

Variables
uint16_t	exposure_ticks
	S13131 exposure time. More...
s13131_ptr	S13131_ddr
s13131_ptr	S13131_port
s13131_ptr	S13131_pin
s13131_ptr	S13131_TCCR0A
s13131_ptr	S13131_TCCR0B
s13131_ptr	S13131_TIFR0
s13131_ptr	S13131_OCR0A
s13131_ptr	S13131_OCR0B
s13131_pin	S13131_Clk
s13131_pin	S13131_St
s13131_pin	S13131_Eos
s13131_bit	S13131_WGM00
s13131_bit	S13131_WGM01
s13131_bit	S13131_WGM02
s13131_bit	S13131_CS00
s13131_bit	S13131_CS01
s13131_bit	S13131_CS02
s13131_bit	S13131_COM0B0
s13131_bit	S13131_COM0B1
s13131_bit	S13131_OCF0A
s13131_bit	S13131_OCF0B

Detailed Description

API

void S13131PinSetup(void);
void S13131StartClocking(void);
void S13131Expose(void);
S13131Readout is defined in VisCmd

Definition in file S13131.h.

Function Documentation

LSB()

uint8_t LSB ( uint16_t  msb_lsb )

inline

LSB behavior:

• returns least significant bit of 16bit input
  

Definition at line 38 of file S13131.h.

MSB()

uint8_t MSB ( uint16_t  msb_lsb )

inline

MSB behavior:

• returns most significant bit of 16bit input
  

Definition at line 31 of file S13131.h.

S13131Expose()

void S13131Expose ( void  )

inline

Exposure signals:

• ST idles LOW
• ST goes HIGH to start exposure
  • Bring ST HIGH some time prior to a CLK rising edge (easiest is to bring ST HIGH just after a CLK falling edge)
  • Integration time officially starts on the 3rd CLK rising edge with ST HIGH
    • the time period from that 3rd rising edge to the 4th rising edge marks the first cycle of exposure time
• ST goes LOW to end exposure
  • Bring ST LOW some time prior to a CLK rising edge (against, easiest is to do this just after a CLK falling edge)
  • Integration time officially stops on the 9th CLK rising edge with ST LOW

This implies that the minimum integration time is 9 clocks. At 50kHz, each clock is 20µs, so minimum integration time is 180µs.

Example: minimum exposure time

  ┌─── Count all rising edges of CLK starting with first ST HIGH
  │ ┌─ Count rising edges of CLK where ST is LOW
  ↓ ↓
 (x,y)
Exposure clocks -------> 1,0   2,0   3,0   4,1   5,2   6,3   7,4   8,5   9,6   10,7  11,8  12,9
        ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐
 CLK    │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │
      ──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └
                          ↑           ↑     ↑  ↑                                            ↑
     ST HIGH clocked-in: ─┘           │     │  │                                            │
                     exposure START: ─┘     │  │                            exposure STOP: ─┘
                        ST LOW clocked-in: ─┘  │                   on 9th CLK rising-edge
                                               │                              with ST LOW
                        ┌─────────────────┐    │
 ST       IDLE LOW      │                 │    ↓
      ──────────────────┘                 └─────────────────────────────────────────────────────
                        ↑                 ↑
                        │                 │
    Wait for CLK LOW    │                 │ 
      to pull ST HIGH: ─┘                 │
                       Wait for CLK LOW   │
                         to pull ST LOW: ─┘

Relationship between exposure and readout:

• exposure ends on the 9th CLK rising edge with ST LOW
• sample first pixel on the 14th CLK falling edge with ST LOW

Therefore, readout always starts 13.5 clocks after ST LOW.

Example: ST HIGH for 3 clocks (4 CLK rising edges)
This corresponds to an integration time of 10 clocks (200 µs)

   Pixel count ---------------------------------------------------------------------------------------------------------------------> 001---002-││511---512---
                                                                                                                                      ┌──┌──┌──┌││┌──┌──┌──┌──
                                                                                                                                      ↓  │--│  ││││  │--│  │--
14th TRIG rising-edge (CLK falling-edge) with ST LOW: ────────────────────────────────────────────────────────────────────────────────┐  │--│  ││││  │--│  │--
First TRIG rising-edge (CLK falling-edge) with ST LOW: ─┐                                                                             │  │--│  ││││  │--│  │--
                                                        ↓                                                                             ↓  │--│  ││││  │--│  │--
   Clocks waiting for readout to start ---------------> 1     2     3     4     5     6     7     8     9     10    11    12    13    14 │--│  ││││  │--│  │--
   Exposure clocks --------> 1,0   2,0   3,0   4,0   5,1   6,2   7,3   8,4   9,5   10,6  11,7  12,8  13,9     ↓     ↓     ↓     ↓     ↓  ↓  ↓  ↓││↓  ↓  ↓  ↓  
           ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌──┐  ┌││┐  ┌──┐  ┌──
    CLK    │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  │  ││││  │  │  │  
         ──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘  └──┘││└──┘  └──┘  
                             ↑           ↑           ↑  ↑                                            ↑
        ST HIGH clocked-in: ─┘           │           │  │                                            │
                        exposure START: ─┘           │  │                            exposure STOP: ─┘
                                 ST LOW clocked-in: ─┘  │                   on 9th CLK rising-edge
                                                        │                              with ST LOW
                           ┌───────────────────────┐    │
    ST       IDLE LOW      │                       │    ↓
         ──────────────────┘                       └────────────────────────────────────────────────────────
                           ↑                       ↑
                           │                       │
       Wait for CLK LOW    │    Wait for CLK LOW   │
         to pull ST HIGH: ─┘      to pull ST LOW: ─┘

Definition at line 191 of file S13131.h.

Variable Documentation

exposure_ticks

uint16_t exposure_ticks

extern

S13131 exposure time.

• exposure is a 16-bit word
• exposure is in units of clock ticks
• multiply exposure by 20e-6 seconds to get exposure time in seconds
  • one clock tick is 20e-6 seconds because the S13131 is clocked at 50kHz
• minimum allowed exposure time is 180e-6 seconds (exposure_ticks = 9)
• exposure_ticks is clamped at 9 ticks
  • exposure_ticks is set to 9 if SetExposure attempts a value < 9

S13131 exposure time.

• exposure is a 16-bit word
• exposure is in units of clock ticks
• multiply exposure by 20e-6 seconds to get exposure time in seconds
  • one clock tick is 20e-6 seconds because the LIS-770i is clocked at 50kHz

Definition at line 32 of file Lis.c.