bachir/vbox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases 1 Wiki Activity

better usb connector for programming, removed prog & serial pads

Browse Source
This commit is contained in:
Bachir Soussi Chiadmi 2025-02-10 22:38:21 +01:00
parent 6cef8b5464
commit fd3841cab1
8 changed files with 8909 additions and 14997 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
boxmod-billofmaterial.csv
View File

@ -2,37 +2,27 @@
"BT1","Liion 18650","Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical","1","" "BT1","Liion 18650","Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical","1",""
"C1,C2,C3","0.1µf","Capacitor_SMD:C_0805_2012Metric","3","" "C1,C2,C3","0.1µf","Capacitor_SMD:C_0805_2012Metric","3",""
"C4,C10,C11,C12,C13,C14","1µF","Capacitor_SMD:C_0805_2012Metric","6","" "C4,C10,C11,C12,C13,C14","1µF","Capacitor_SMD:C_0805_2012Metric","6",""
"C5,C8","10µF","Capacitor_SMD:C_0805_2012Metric","2","" "C5","10µF","Capacitor_SMD:C_0805_2012Metric","1",""
"C6,C15","22pF","Capacitor_SMD:C_0805_2012Metric","2","" "C6,C15","22pF","Capacitor_SMD:C_0805_2012Metric","2",""
"C7,C20,C21","0.1µF","Capacitor_SMD:C_0805_2012Metric","3","" "C7,C20,C21","0.1µF","Capacitor_SMD:C_0805_2012Metric","3",""
"C9","22µF","Capacitor_SMD:C_0805_2012Metric","1","" "C16,C17","1µf","Capacitor_SMD:C_0805_2012Metric","2",""
"C16,C17","10µf","Capacitor_SMD:C_0805_2012Metric","2",""
"DS1","OLED-DD-9616BE-3A","My_footprint:oled DD-9616BE-3A_fliped(folded)","1","" "DS1","OLED-DD-9616BE-3A","My_footprint:oled DD-9616BE-3A_fliped(folded)","1",""
"J1","USB_C_Receptacle_PowerOnly_6P","My_footprint:CUI_UJC-VP-3-SMT-TR","1",""
"J2","serial pads","My_footprint:pad-probe_1x04_P1.27mm_Vertical","1",""
"J3","ICSP like pads","My_footprint:pad-probe_2x03_P1.27mm_Vertical","1",""
"J4,J5","Conn_01x01_Pin","Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical","2","" "J4,J5","Conn_01x01_Pin","Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical","2",""
"J6","GCT_USB4120-03-C_REVA","My_footprint:GCT_USB4120-03-C_REVA","1",""
"L1","560nH","Inductor_SMD:L_0805_2012Metric","1","" "L1","560nH","Inductor_SMD:L_0805_2012Metric","1",""
"L2","1µH","Inductor_SMD:L_0805_2012Metric","1",""
"Q1","FS8205A","Package_SO:TSSOP-8_4.4x3mm_P0.65mm","1","" "Q1","FS8205A","Package_SO:TSSOP-8_4.4x3mm_P0.65mm","1",""
"Q2","AO3400A","Package_TO_SOT_SMD:SOT-23","1","" "Q3,Q6","AO3401A","Package_TO_SOT_SMD:SOT-23","2",""
"Q3","AO3401A","Package_TO_SOT_SMD:SOT-23","1",""
"Q4","BSS138","Package_TO_SOT_SMD:SOT-23","1","" "Q4","BSS138","Package_TO_SOT_SMD:SOT-23","1",""
"Q5","IRLML6344","Package_TO_SOT_SMD:SOT-23","1",""
"R1","2K","Resistor_SMD:R_0805_2012Metric","1","" "R1","2K","Resistor_SMD:R_0805_2012Metric","1",""
"R2","390k","Resistor_SMD:R_0805_2012Metric","1","" "R2","390k","Resistor_SMD:R_0805_2012Metric","1",""
"R3,R13,R15,R17,R18,R19","10k","Resistor_SMD:R_0805_2012Metric","6","" "R3,R6,R7,R15,R18","10k","Resistor_SMD:R_0805_2012Metric","5",""
"R4","1k","Resistor_SMD:R_0805_2012Metric","1","" "R4","1k","Resistor_SMD:R_0805_2012Metric","1",""
"R5","100","Resistor_SMD:R_0805_2012Metric","1","" "R5","100","Resistor_SMD:R_0805_2012Metric","1",""
"R6,R7,R8","10K","Resistor_SMD:R_0805_2012Metric","3",""
"R9","1r","Resistor_SMD:R_0805_2012Metric","1","" "R9","1r","Resistor_SMD:R_0805_2012Metric","1",""
"R10","732k","Resistor_SMD:R_0805_2012Metric","1","" "R14,R16","100r","Resistor_SMD:R_0805_2012Metric","2",""
"R11","100k","Resistor_SMD:R_0805_2012Metric","1",""
"R12,R14,R16","100r","Resistor_SMD:R_0805_2012Metric","3",""
"SW1,SW2,SW3","SW_Push","-- mixed values --","3","" "SW1,SW2,SW3","SW_Push","-- mixed values --","3",""
"U1","TP4056","My_footprint:SOP127P600X175-9N","1","" "U1","TP4056","My_footprint:SOP127P600X175-9N","1",""
"U2","DW01A","Package_TO_SOT_SMD:SOT-23-6","1","" "U2","DW01A","Package_TO_SOT_SMD:SOT-23-6","1",""
"U3","ATSAMD21G18A-A","Package_QFP:TQFP-48_7x7mm_P0.5mm","1","" "U3","ATSAMD21G18A-A","Package_QFP:TQFP-48_7x7mm_P0.5mm","1",""
"U4","HT7133-SOT89","Package_TO_SOT_SMD:SOT-89-3","1","" "U4","AP2112K-3.3","Package_TO_SOT_SMD:SOT-23-5","1",""
"U5","TPS61022","Package_DFN_QFN:Texas_RWU0007A_VQFN-7_2x2mm_P0.5mm","1",""
"Y1","Crystal","Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm","1","" "Y1","Crystal","Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm","1",""

1 Reference Value Footprint Qty DNP
2 BT1 Liion 18650 Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical 1
3 C1,C2,C3 0.1µf Capacitor_SMD:C_0805_2012Metric 3
4 C4,C10,C11,C12,C13,C14 1µF Capacitor_SMD:C_0805_2012Metric 6
5 C5,C8 C5 10µF Capacitor_SMD:C_0805_2012Metric 2 1
6 C6,C15 22pF Capacitor_SMD:C_0805_2012Metric 2
7 C7,C20,C21 0.1µF Capacitor_SMD:C_0805_2012Metric 3
8 C9 C16,C17 22µF 1µf Capacitor_SMD:C_0805_2012Metric 1 2
C16,C17 10µf Capacitor_SMD:C_0805_2012Metric 2
9 DS1 OLED-DD-9616BE-3A My_footprint:oled DD-9616BE-3A_fliped(folded) 1
J1 USB_C_Receptacle_PowerOnly_6P My_footprint:CUI_UJC-VP-3-SMT-TR 1
J2 serial pads My_footprint:pad-probe_1x04_P1.27mm_Vertical 1
J3 ICSP like pads My_footprint:pad-probe_2x03_P1.27mm_Vertical 1
10 J4,J5 Conn_01x01_Pin Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical 2
11 J6 GCT_USB4120-03-C_REVA My_footprint:GCT_USB4120-03-C_REVA 1
12 L1 560nH Inductor_SMD:L_0805_2012Metric 1
L2 1µH Inductor_SMD:L_0805_2012Metric 1
13 Q1 FS8205A Package_SO:TSSOP-8_4.4x3mm_P0.65mm 1
14 Q2 Q3,Q6 AO3400A AO3401A Package_TO_SOT_SMD:SOT-23 1 2
Q3 AO3401A Package_TO_SOT_SMD:SOT-23 1
15 Q4 BSS138 Package_TO_SOT_SMD:SOT-23 1
Q5 IRLML6344 Package_TO_SOT_SMD:SOT-23 1
16 R1 2K Resistor_SMD:R_0805_2012Metric 1
17 R2 390k Resistor_SMD:R_0805_2012Metric 1
18 R3,R13,R15,R17,R18,R19 R3,R6,R7,R15,R18 10k Resistor_SMD:R_0805_2012Metric 6 5
19 R4 1k Resistor_SMD:R_0805_2012Metric 1
20 R5 100 Resistor_SMD:R_0805_2012Metric 1
R6,R7,R8 10K Resistor_SMD:R_0805_2012Metric 3
21 R9 1r Resistor_SMD:R_0805_2012Metric 1
22 R10 R14,R16 732k 100r Resistor_SMD:R_0805_2012Metric 1 2
R11 100k Resistor_SMD:R_0805_2012Metric 1
R12,R14,R16 100r Resistor_SMD:R_0805_2012Metric 3
23 SW1,SW2,SW3 SW_Push -- mixed values -- 3
24 U1 TP4056 My_footprint:SOP127P600X175-9N 1
25 U2 DW01A Package_TO_SOT_SMD:SOT-23-6 1
26 U3 ATSAMD21G18A-A Package_QFP:TQFP-48_7x7mm_P0.5mm 1
27 U4 HT7133-SOT89 AP2112K-3.3 Package_TO_SOT_SMD:SOT-89-3 Package_TO_SOT_SMD:SOT-23-5 1
U5 TPS61022 Package_DFN_QFN:Texas_RWU0007A_VQFN-7_2x2mm_P0.5mm 1
28 Y1 Crystal Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm 1

68
boxmod-billofmaterial.md
View File

@ -1,39 +1,29 @@
| Reference | Value | Footprint | Qty | DNP | | Reference | Value | Footprint | Qty |
| ---------------------- | ----------------------------- | ---------------------------------------------------------- | --- | --- | |------------------------|-----------------------|------------------------------------------------------------|-----|
| BT1 | Liion 18650 | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | 1 | | | BT1 | Liion 18650 | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | 1 |
| C1,C2,C3 | 0.1µf | Capacitor_SMD:C_0805_2012Metric | 3 | | | C1,C2,C3 | 0.1µf | Capacitor_SMD:C_0805_2012Metric | 3 |
| C4,C10,C11,C12,C13,C14 | 1µF | Capacitor_SMD:C_0805_2012Metric | 6 | | | C4,C10,C11,C12,C13,C14 | 1µF | Capacitor_SMD:C_0805_2012Metric | 6 |
| C5,C8 | 10µF | Capacitor_SMD:C_0805_2012Metric | 2 | | | C5 | 10µF | Capacitor_SMD:C_0805_2012Metric | 1 |
| C6,C15 | 22pF | Capacitor_SMD:C_0805_2012Metric | 2 | | | C6,C15 | 22pF | Capacitor_SMD:C_0805_2012Metric | 2 |
| C7,C20,C21 | 0.1µF | Capacitor_SMD:C_0805_2012Metric | 3 | | | C7,C20,C21 | 0.1µF | Capacitor_SMD:C_0805_2012Metric | 3 |
| C9 | 22µF | Capacitor_SMD:C_0805_2012Metric | 1 | | | C16,C17 | 1µf | Capacitor_SMD:C_0805_2012Metric | 2 |
| C16,C17 | 10µf | Capacitor_SMD:C_0805_2012Metric | 2 | | | DS1 | OLED-DD-9616BE-3A | My_footprint:oled DD-9616BE-3A_fliped(folded) | 1 |
| DS1 | OLED-DD-9616BE-3A | My_footprint:oled DD-9616BE-3A_fliped(folded) | 1 | | | J4,J5 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | 2 |
| J1 | USB_C_Receptacle_PowerOnly_6P | My_footprint:CUI_UJC-VP-3-SMT-TR | 1 | | | J6 | GCT_USB4120-03-C_REVA | My_footprint:GCT_USB4120-03-C_REVA | 1 |
| J2 | serial pads | My_footprint:pad-probe_1x04_P1.27mm_Vertical | 1 | | | L1 | 560nH | Inductor_SMD:L_0805_2012Metric | 1 |
| J3 | ICSP like pads | My_footprint:pad-probe_2x03_P1.27mm_Vertical | 1 | | | Q1 | FS8205A | Package_SO:TSSOP-8_4.4x3mm_P0.65mm | 1 |
| J4,J5 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | 2 | | | Q3,Q6 | AO3401A | Package_TO_SOT_SMD:SOT-23 | 2 |
| L1 | 560nH | Inductor_SMD:L_0805_2012Metric | 1 | | | Q4 | BSS138 | Package_TO_SOT_SMD:SOT-23 | 1 |
| L2 | 1µH | Inductor_SMD:L_0805_2012Metric | 1 | | | R1 | 2K | Resistor_SMD:R_0805_2012Metric | 1 |
| Q1 | FS8205A | Package_SO:TSSOP-8_4.4x3mm_P0.65mm | 1 | | | R2 | 390k | Resistor_SMD:R_0805_2012Metric | 1 |
| Q2 | AO3400A | Package_TO_SOT_SMD:SOT-23 | 1 | | | R3,R6,R7,R15,R18 | 10k | Resistor_SMD:R_0805_2012Metric | 5 |
| Q3 | AO3401A | Package_TO_SOT_SMD:SOT-23 | 1 | | | R4 | 1k | Resistor_SMD:R_0805_2012Metric | 1 |
| Q4 | BSS138 | Package_TO_SOT_SMD:SOT-23 | 1 | | | R5 | 100 | Resistor_SMD:R_0805_2012Metric | 1 |
| Q5 | IRLML6344 | Package_TO_SOT_SMD:SOT-23 | 1 | | | R9 | 1r | Resistor_SMD:R_0805_2012Metric | 1 |
| R1 | 2K | Resistor_SMD:R_0805_2012Metric | 1 | | | R14,R16 | 100r | Resistor_SMD:R_0805_2012Metric | 2 |
| R2 | 390k | Resistor_SMD:R_0805_2012Metric | 1 | | | SW1,SW2,SW3 | SW_Push | -- mixed values -- | 3 |
| R3,R13,R15,R17,R18,R19 | 10k | Resistor_SMD:R_0805_2012Metric | 6 | | | U1 | TP4056 | My_footprint:SOP127P600X175-9N | 1 |
| R4 | 1k | Resistor_SMD:R_0805_2012Metric | 1 | | | U2 | DW01A | Package_TO_SOT_SMD:SOT-23-6 | 1 |
| R5 | 100 | Resistor_SMD:R_0805_2012Metric | 1 | | | U3 | ATSAMD21G18A-A | Package_QFP:TQFP-48_7x7mm_P0.5mm | 1 |
| R6,R7,R8 | 10K | Resistor_SMD:R_0805_2012Metric | 3 | | | U4 | AP2112K-3.3 | Package_TO_SOT_SMD:SOT-23-5 | 1 |
| R9 | 1r | Resistor_SMD:R_0805_2012Metric | 1 | | | Y1 | Crystal | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | 1 |
| R10 | 732k | Resistor_SMD:R_0805_2012Metric | 1 | |
| R11 | 100k | Resistor_SMD:R_0805_2012Metric | 1 | |
| R12,R14,R16 | 100r | Resistor_SMD:R_0805_2012Metric | 3 | |
| SW1,SW2,SW3 | SW_Push | -- mixed values -- | 3 | |
| U1 | TP4056 | My_footprint:SOP127P600X175-9N | 1 | |
| U2 | DW01A | Package_TO_SOT_SMD:SOT-23-6 | 1 | |
| U3 | ATSAMD21G18A-A | Package_QFP:TQFP-48_7x7mm_P0.5mm | 1 | |
| U4 | HT7133-SOT89 | Package_TO_SOT_SMD:SOT-89-3 | 1 | |
| U5 | TPS61022 | Package_DFN_QFN:Texas_RWU0007A_VQFN-7_2x2mm_P0.5mm | 1 | |
| Y1 | Crystal | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | 1 | |

12513
boxmod.kicad_pcb
View File

File diff suppressed because it is too large Load Diff

7899
boxmod.kicad_sch
View File

File diff suppressed because it is too large Load Diff

3332
fp-info-cache
View File

File diff suppressed because it is too large Load Diff

70
readme.md
View File

@ -6,7 +6,7 @@ custom boxmod chipset from scratch
# schematic # schematic
![schematics](./schematics-v0.3.1.png) ![schematics](./schematics-v0.3.2.png)
# 3D # 3D
![front](./boxmod-3Dview-front.png) ![front](./boxmod-3Dview-front.png)
@ -15,42 +15,32 @@ custom boxmod chipset from scratch
# bill of materials # bill of materials
| Reference | Value | Footprint | Qty | DNP | | Reference | Value | Footprint | Qty |
| ---------------------- | ----------------------------- | ---------------------------------------------------------- | --- | --- | |------------------------|-----------------------|------------------------------------------------------------|-----|
| BT1 | Liion 18650 | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | 1 | | | BT1 | Liion 18650 | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | 1 |
| C1,C2,C3 | 0.1µf | Capacitor_SMD:C_0805_2012Metric | 3 | | | C1,C2,C3 | 0.1µf | Capacitor_SMD:C_0805_2012Metric | 3 |
| C4,C10,C11,C12,C13,C14 | 1µF | Capacitor_SMD:C_0805_2012Metric | 6 | | | C4,C10,C11,C12,C13,C14 | 1µF | Capacitor_SMD:C_0805_2012Metric | 6 |
| C5,C8 | 10µF | Capacitor_SMD:C_0805_2012Metric | 2 | | | C5 | 10µF | Capacitor_SMD:C_0805_2012Metric | 1 |
| C6,C15 | 22pF | Capacitor_SMD:C_0805_2012Metric | 2 | | | C6,C15 | 22pF | Capacitor_SMD:C_0805_2012Metric | 2 |
| C7,C20,C21 | 0.1µF | Capacitor_SMD:C_0805_2012Metric | 3 | | | C7,C20,C21 | 0.1µF | Capacitor_SMD:C_0805_2012Metric | 3 |
| C9 | 22µF | Capacitor_SMD:C_0805_2012Metric | 1 | | | C16,C17 | 1µf | Capacitor_SMD:C_0805_2012Metric | 2 |
| C16,C17 | 10µf | Capacitor_SMD:C_0805_2012Metric | 2 | | | DS1 | OLED-DD-9616BE-3A | My_footprint:oled DD-9616BE-3A_fliped(folded) | 1 |
| DS1 | OLED-DD-9616BE-3A | My_footprint:oled DD-9616BE-3A_fliped(folded) | 1 | | | J4,J5 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | 2 |
| J1 | USB_C_Receptacle_PowerOnly_6P | My_footprint:CUI_UJC-VP-3-SMT-TR | 1 | | | J6 | GCT_USB4120-03-C_REVA | My_footprint:GCT_USB4120-03-C_REVA | 1 |
| J2 | serial pads | My_footprint:pad-probe_1x04_P1.27mm_Vertical | 1 | | | L1 | 560nH | Inductor_SMD:L_0805_2012Metric | 1 |
| J3 | ICSP like pads | My_footprint:pad-probe_2x03_P1.27mm_Vertical | 1 | | | Q1 | FS8205A | Package_SO:TSSOP-8_4.4x3mm_P0.65mm | 1 |
| J4,J5 | Conn_01x01_Pin | Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical | 2 | | | Q3,Q6 | AO3401A | Package_TO_SOT_SMD:SOT-23 | 2 |
| L1 | 560nH | Inductor_SMD:L_0805_2012Metric | 1 | | | Q4 | BSS138 | Package_TO_SOT_SMD:SOT-23 | 1 |
| L2 | 1µH | Inductor_SMD:L_0805_2012Metric | 1 | | | R1 | 2K | Resistor_SMD:R_0805_2012Metric | 1 |
| Q1 | FS8205A | Package_SO:TSSOP-8_4.4x3mm_P0.65mm | 1 | | | R2 | 390k | Resistor_SMD:R_0805_2012Metric | 1 |
| Q2 | AO3400A | Package_TO_SOT_SMD:SOT-23 | 1 | | | R3,R6,R7,R15,R18 | 10k | Resistor_SMD:R_0805_2012Metric | 5 |
| Q3 | AO3401A | Package_TO_SOT_SMD:SOT-23 | 1 | | | R4 | 1k | Resistor_SMD:R_0805_2012Metric | 1 |
| Q4 | BSS138 | Package_TO_SOT_SMD:SOT-23 | 1 | | | R5 | 100 | Resistor_SMD:R_0805_2012Metric | 1 |
| Q5 | IRLML6344 | Package_TO_SOT_SMD:SOT-23 | 1 | | | R9 | 1r | Resistor_SMD:R_0805_2012Metric | 1 |
| R1 | 2K | Resistor_SMD:R_0805_2012Metric | 1 | | | R14,R16 | 100r | Resistor_SMD:R_0805_2012Metric | 2 |
| R2 | 390k | Resistor_SMD:R_0805_2012Metric | 1 | | | SW1,SW2,SW3 | SW_Push | -- mixed values -- | 3 |
| R3,R13,R15,R17,R18,R19 | 10k | Resistor_SMD:R_0805_2012Metric | 6 | | | U1 | TP4056 | My_footprint:SOP127P600X175-9N | 1 |
| R4 | 1k | Resistor_SMD:R_0805_2012Metric | 1 | | | U2 | DW01A | Package_TO_SOT_SMD:SOT-23-6 | 1 |
| R5 | 100 | Resistor_SMD:R_0805_2012Metric | 1 | | | U3 | ATSAMD21G18A-A | Package_QFP:TQFP-48_7x7mm_P0.5mm | 1 |
| R6,R7,R8 | 10K | Resistor_SMD:R_0805_2012Metric | 3 | | | U4 | AP2112K-3.3 | Package_TO_SOT_SMD:SOT-23-5 | 1 |
| R9 | 1r | Resistor_SMD:R_0805_2012Metric | 1 | | | Y1 | Crystal | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | 1 |
| R10 | 732k | Resistor_SMD:R_0805_2012Metric | 1 | |
| R11 | 100k | Resistor_SMD:R_0805_2012Metric | 1 | |
| R12,R14,R16 | 100r | Resistor_SMD:R_0805_2012Metric | 3 | |
| SW1,SW2,SW3 | SW_Push | -- mixed values -- | 3 | |
| U1 | TP4056 | My_footprint:SOP127P600X175-9N | 1 | |
| U2 | DW01A | Package_TO_SOT_SMD:SOT-23-6 | 1 | |
| U3 | ATSAMD21G18A-A | Package_QFP:TQFP-48_7x7mm_P0.5mm | 1 | |
| U4 | HT7133-SOT89 | Package_TO_SOT_SMD:SOT-89-3 | 1 | |
| U5 | TPS61022 | Package_DFN_QFN:Texas_RWU0007A_VQFN-7_2x2mm_P0.5mm | 1 | |
| Y1 | Crystal | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | 1 | |

BIN
schematics-v0.3.2.pdf Normal file
View File

Binary file not shown.

BIN
schematics-v0.3.2.png Normal file
View File

Binary file not shown.
Side by Side

After

Width:  |  Height:  |  Size: 308 KiB