This page describes the result of measurements, which pin is connected to where.
There is online not much information available about the ChiTu F X board. The following pdf is what I collected from a search through the internet:
List of components:
A logic analyzer capture of the communication between printer controller and lcd controller: (png images, 4.2MB) can be found here:
Connection diagram ChiTu F X series V4.3 191205-FX U8 IC:STM32F446ZET6, LQFP 144 pin 54 PF14 -> U6_E1,P.2 (E1-EN) 47 PB1 -> U6_E1,P.16 (E1-STP) 53 PF13 -> U6_E1,P.19 (E1-DIR) 89 PG4 -> U6_E2,P.2 (E2-EN) 82 PD13 -> U6_E2,P.16 (E2-STP) 90 PG5 -> U6_E2,P.19 (E2-DIR) 10 PF0 -> U6_X,P.2 (X-EN) 04 PE5 -> U6_X,P.16 (X-STP) 11 PF1 -> U6_X,P.19 (X-DIR) 15 PF5 -> U6_Y,P.2 (Y-EN) 21 PF9 -> U6_Y,P.16 (Y-STP) 13 PF3 -> U6_Y,P.19 (Y-DIR) 41 PA5 -> U6_Z,P.2 (Z-EN) 42 PA6 -> U6_Z,P.16 (Z-STP) 55 PF15 -> U6_Z,P.19 (Z-DIR) 93 PG8 -> Q5,P.G (E1_HOT) 110 PA15 -> Q20,P.G (E2_HOT) 73 PB12 -> U4,P.12 (LCD RESET) 85 PD14 -> U4,P.35 (LCD D0) 86 PD15 -> U4,P.34 (LCD D1) 114 PD0 -> U4,P.33 (LCD D2 115 PD1 -> U4,P.32 (LCD D3) 58 PE7 -> U4,P.26 (LCD D4) 63 PE8 -> U4,P.11 (LCD D5) 60 PE9 -> U4,P.10 (LCD D6) 63 PE10 -> U4,P.9 (LCD D7) 64 PE11 -> U4,P.25 (LCD D8) 65 PE12 -> U4,P.24 (LCD D9) 66 PE13 -> U4,P.23 (LCD D10) 67 PE14 -> U4,P.22 (LCD D11) 68 PE15 -> U4,P.21 (LCD D12) 77 PD8 -> U4,P.20 (LCD D13) 78 PD9 -> U4,P.10 (LCD D14) 79 PD10 -> U4,P.18 (LCD D15) 73 PB12 -> U4,P.12 (LCD RESET) etc. (See below) >>>>>>>>>>>>> Todo: 13 XPT2046,P.16 SPI1-SCK 14 XPT2046,P.15 SPI1-_CS 15 XPT2046,P.14 SPI1-MOSI 16 XPT2046,P.12 SPI1-MISO 17 XPT2046,P.11 SPI1-INT 27 -> (U8,P.93/PG8) LIGHT PWM #B4 28 -> (U8,P.118/PD4) LCD-nOE #B3 29 -> (U8,P.119/PD5) LCD-nWE #B2 (Active low) ?? 30 -> (U8,P.87/PG2) RS #B1 31 -> (U8,P.127/PG12) PS-CLK #B0 / Chip select ?? <<<<<<<<<<<<<< U6_E1 IC:TMC2209-LA 01 OB2 (E1-MOTOR,P.2B) 02 ENN (U8,P.54/PF14) 03 GND 04 CPO 05 CPI 06 VCP 07 SPREAD 08 5VOUT 09 MS1_AD0 10 MS2_AD1 11 DIAG 12 INDEX 13 CLK 14 PDN_UART 15 VCC_IO 16 STEP (U8,P.47/PB1) 17 VREF 18 GND 19 DIR (U8,P.53/PF13) 20 STDBY 21 OA2 (E1-MOTOR,P.1B) 22 VS 23 BRA 24 OA1 (E1-MOTOR,P.1A) 25 . 26 OB1 (E1-MOTOR,P.2A) 27 BRB 28 VS U6_E2 IC:TMC2209-LA 01 OB2 (E2/EXT-MOTOR,P.2B) 02 ENN (U8,P.89/PG4) 03 GND 04 CPO 05 CPI 06 VCP 07 SPREAD 08 5VOUT 09 MS1_AD0 10 MS2_AD1 11 DIAG 12 INDEX 13 CLK 14 PDN_UART 15 VCC_IO 16 STEP (U8,P.82/PD13) 17 VREF 18 GND 19 DIR (U8,P.90/PG5) 20 STDBY 21 OA2 (E2/EXT-MOTOR,P.1B) 22 VS 23 BRA 24 OA1 (E2/EXT-MOTOR,P.1A) 25 . 26 OB1 (E2/EXT-MOTOR,P.2A) 27 BRB 28 VS U6_X IC:TMC2209-LA 01 OB2 (X-MOTOR,P.2B) 02 ENN (U8,P.10/PF0) 03 GND 04 CPO 05 CPI 06 VCP 07 SPREAD 08 5VOUT 09 MS1_AD0 10 MS2_AD1 11 DIAG 12 INDEX 13 CLK 14 PDN_UART 15 VCC_IO 16 STEP (U8,P.04/PE5) 17 VREF 18 GND 19 DIR (U8,P.11/PF1) 20 STDBY 21 OA2 (X-MOTOR,P.1B) 22 VS 23 BRA 24 OA1 (X-MOTOR,P.1A) 25 . 26 OB1 (X-MOTOR,P.2A) 27 BRB 28 VS U6_Y IC:TMC2209-LA 01 OB2 (Y-MOTOR,P.2B) 02 ENN (U8,P.15/PF5) 03 GND 04 CPO 05 CPI 06 VCP 07 SPREAD 08 5VOUT 09 MS1_AD0 10 MS2_AD1 11 DIAG 12 INDEX 13 CLK 14 PDN_UART 15 VCC_IO 16 STEP (U8,P.21/PF9) 17 VREF 18 GND 19 DIR (U8,P.13/PF3) 20 STDBY 21 OA2 (Y-MOTOR,P.1B) 22 VS 23 BRA 24 OA1 (Y-MOTOR,P.1A) 25 . 26 OB1 (Y-MOTOR,P.2A) 27 BRB 28 VS U6_Z IC:TMC2209-LA 01 OB2 (Z-MOTOR,P.2B) 02 ENN (U8,P.41/PA5) 03 GND 04 CPO 05 CPI 06 VCP 07 SPREAD 08 5VOUT 09 MS1_AD0 10 MS2_AD1 11 DIAG 12 INDEX 13 CLK 14 PDN_UART 15 VCC_IO 16 STEP (U8,P.42/PA6) 17 VREF 18 GND 19 DIR (U8,P.55/PF15) 20 STDBY 21 OA2 (Z-MOTOR,P.1B) 22 VS 23 BRA 24 OA1 (Z-MOTOR,P.1A) 25 . 26 OB1 (Z-MOTOR,P.2A) 27 BRB 28 VS E1-MOTOR J:4 pin JST conn 1B U6-E1,P.21 1A U6-E1,P.24 2A U6-E1,P.26 2B U6-E1,P.1 E2/EXT-MOTOR J:4 pin JST conn 1B U6-E2,P.21 1A U6-E2,P.24 2A U6-E2,P.26 2B U6-E2,P.1 X-MOTOR J:4 pin JST conn 1B U6-X,P.21 1A U6-X,P.24 2A U6-X,P.26 2B U6-X,P.1 Y-MOTOR J:4 pin JST conn 1B U6-Y,P.21 1A U6-Y,P.24 2A U6-Y,P.26 2B U6-Y,P.1 Z-MOTOR J:4 pin JST conn 1B U6-Z,P.21 1A U6-Z,P.24 2A U6-Z,P.26 2B U6-Z,P.1 E1_HOT J:2-pin screw terminal 5.08mm E1 GND HOT <- Q5,P.D E2_HOT J:2-pin screw terminal 5.08mm E2 GND HOT Q5 TR:WSF40N06, N-Ch. Mosfet (60v, 20mOhm, 50A) G <- R42,P.1 + U8,P.93 (PG8) D -> E1_HOT,P.HOT S <- +12/24V R42 R:01C (10k, 1%) 1 Q5,P.G 2 GND Q20 TR:WSF40N06, N-Ch. Mosfet (60v, 20mOhm, 50A) G <- R21,P.1 + U8,P.110 (PA15) D -> E2_HOT,P.HOT S <- +12/24V R21 R:01C (10k, 1%) 1 Q20,P.G 2 GND
Below is the pinout from the FPC cable (FPC-350C40119V1)
Please note that logic analyzer pin is given after #-character
Connector U4
1 VCC_3.3V 2 VCC_3.3V 3 VCC_3.3V 4 VCC_5V 5 VCC_5V 6 GND 7 GND 8 GND 9 -> (U8,P.63/PE10) D7 #A7 10 -> (U8,P.60/PE9) D6 #A6 11 -> (U8,P.63/PE8) D5 #A5 12 -> (U8,P.73/PB12) LCD RESET #B5 13 XPT2046,P.16 SPI1-SCK 14 XPT2046,P.15 SPI1-_CS 15 XPT2046,P.14 SPI1-MOSI 16 XPT2046,P.12 SPI1-MISO 17 XPT2046,P.11 SPI1-INT 18 -> (U8,P.79/PD10) D15 #A15 19 -> (U8,P.78/PD9) D14 #A14 20 -> (U8,P.77/PD8) D13 #A13 21 -> (U8,P.68/PE15) D12 #A12 22 -> (U8,P.67/PE14) D11 #A11 23 -> (U8,P.66/PE13) D10 #A10 24 -> (U8,P.65/PE12) D9 #A9 25 -> (U8,P.64/PE11) D8 #A8 26 -> (U8,P.58/PE7) D4 #A4 27 -> (U8,P.93/PG8) LIGHT PWM #B4 28 -> (U8,P.118/PD4) LCD-nOE #B3 29 -> (U8,P.119/PD5) LCD-nWE #B2 (Active low) ?? 30 -> (U8,P.87/PG2) RS #B1 31 -> (U8,P.127/PG12) PS-CLK #B0 / Chip select ?? 32 -> (U8,P.115/PD1) D3 #A3 33 -> (U8,P.114/PD0) D2 #A2 34 -> (U8,P.86/PD15) D1 #A1 35 -> (U8,P.85/PD14) D0 #A0 36 GND 37 NC (EXT_ENC_B) 38 NC (EXT_ENC_A) 39 NC (EXT_ENC_PRESS) 40 VCC_3.3V