diff --git a/mcu/st_stm32f042.yaml b/mcu/st_stm32f042.yaml
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+name: STM32F042
+# not all variations added, just as needed
+variations: FxP, GxU
+# not verified: CxT, CxU
+# STM32F042xyz
+# x = pin count: F=20, G=28, K=32, T=36, C=48
+# y = flash size: 4=16KB, 6=32KB
+# z = package: R=TSSOP, T=LQFP, U=UFQFPN, Y=WLCSP
+description: Cortex-M0 USB line MCU
+keywords: MCU, micro-controller
+datasheet: https://www.st.com/resource/en/datasheet/stm32f042g6.pdf
+
+pinout@FxP: # TSSOP20
+  PORTA:
+    PA0: 6
+    PA1: 7
+    PA2: 8
+    PA3: 9
+    PA4: 10
+    PA5: 11
+    PA6: 12
+    PA7: 13
+    PA9-PA11: 17
+    PA10-PA12: 18
+    PA13-SWDIO: 19
+    PA14-SWCLK: 20
+  PORTB:
+    PB1: 14
+    PB8-BOOT0: 1
+  PORTF:
+    PF0-OSC_IN: 2
+    PF1-OSC_OUT: 3
+  CTRL:
+    NRST: 4
+  GROUND:
+    VSS: 15
+  POWER:
+    VDD-VDDIO2: 16
+    VDDA: 5
+
+pinout@GxU: # QFN28
+  PORTA:
+    PA0: 6
+    PA1: 7
+    PA2: 8
+    PA3: 9
+    PA4: 10
+    PA5: 11
+    PA6: 12
+    PA7: 13
+    PA9-PA11: 19
+    PA10-PA12: 20
+    PA13-SWDIO: 21
+    PA14-SWCLK: 22
+    PA15: 23
+  PORTB:
+    PB0: 14
+    PB1: 15
+    PB3: 24
+    PB4: 25
+    PB5: 26
+    PB6: 27
+    PB7: 28
+    PB8-BOOT0: 1
+  PORTF:
+    PF0-OSC_IN: 2
+    PF1-OSC_OUT: 3
+  CTRL:
+    NRST: 4
+  GROUND:
+    VSS: 16
+  POWER:
+    VDD: 17
+    VDDIO2: 18
+    VDDA: 5
+
+pinout@CxT: # LQFP48
+  PORTA:
+    PA0-WKUP: 10
+    PA1: 11
+    PA2: 12
+    PA3: 13
+    PA4: 14
+    PA5: 15
+    PA6: 16
+    PA7: 17
+    PA8: 29
+    PA9: 30
+    PA10: 31
+    PA11: 32
+    PA12: 33
+    PA13: 34
+    PA14: 37
+    PA15: 38
+  PORTB:
+    PB0: 18
+    PB1: 19
+    PB2: 20
+    PB3: 39
+    PB4: 40 
+    PB5: 41
+    PB6: 42
+    PB7: 43
+    PB8: 45
+    PB9: 46
+    PB10: 21
+    PB11: 22
+    PB12: 25
+    PB13: 26
+    PB14: 27
+    PB15: 28
+  PORTC:
+    PC13-TAMPER-RTC: 2
+    PC14-OSC32_IN: 3
+    PC15-OSC32_OUT: 4
+  CTRL:
+    BOOT0: 44
+    OSC_IN: 5
+    OSC_OUT: 6
+    NRST: 7
+  GROUND:
+    VSS: 23, 35, 47
+    VSSA: 8
+  POWER:
+    VDD: 24, 36, 48
+    VDDA: 9
+    VBAT: 1
+
+pinout@CxU: # QFN48
+  PORTA:
+    PA0-WKUP: 10
+    PA1: 11
+    PA2: 12
+    PA3: 13
+    PA4: 14
+    PA5: 15
+    PA6: 16
+    PA7: 17
+    PA8: 29
+    PA9: 30
+    PA10: 31
+    PA11: 32
+    PA12: 33
+    PA13: 34
+    PA14: 37
+    PA15: 38
+  PORTB:
+    PB0: 18
+    PB1: 19
+    PB2: 20
+    PB3: 39
+    PB4: 40 
+    PB5: 41
+    PB6: 42
+    PB7: 43
+    PB8: 45
+    PB9: 46
+    PB10: 21
+    PB11: 22
+    PB12: 25
+    PB13: 26
+    PB14: 27
+    PB15: 28
+  PORTC:
+    PC13-TAMPER-RTC: 2
+    PC14-OSC32_IN: 3
+    PC15-OSC32_OUT: 4
+  CTRL:
+    BOOT0: 44
+    OSC_IN: 5
+    OSC_OUT: 6
+    NRST: 7
+  GROUND:
+    VSS: 23, 35, 47, 49
+    VSSA: 8
+  POWER:
+    VDD: 24, 36, 48
+    VDDA: 9
+    VBAT: 1
+
+properties:
+  in: NRST, BOOT0
+  bidir: PORTA, PORTB, PORTC, PORTF
+  power: VDD, VDDA, VDDIO2, VBAT
+  ground: VSS, VSSA
+  inverted: NRST
+
+schematic:
+  symbol: IC
+  left: PORTA, PORTF
+  right: PORTB, PORTC, CTRL
+  top: POWER
+  bottom: GROUND
+
+housing@FxP: # TSSOP20
+  suffix: FxP
+  pattern: SOP
+  bodyWidth: 4.3-4.5 # E1
+  bodyLength: 6.4-6.6 # D
+  height: 1.2 # A
+  leadWidth: 0.19-0.30 # b
+  leadLength: 0.45-0.75 # L
+  leadSpan: 6.2-6.6 # E
+  pitch: 0.65 # e
+  leadCount: 20
+
+housing@GxU: # QFN28
+  suffix: GxU
+  pattern: QFN
+  bodyWidth: 3.9-4.1 # D
+  bodyLength: 3.9-4.1 # E
+  height: 0.5-0.6 # A
+  leadWidth: 0.2-0.3 # b
+  leadLength: 0.3-0.5 # L
+  pitch: 0.5 # e
+  leadCount: 28
+  rowCount: 7
+  columnCount: 7
+  # no tab
+
+housing@CxU: # QFN48
+  suffix: CxU
+  pattern: QFN
+  bodyWidth: 7.0
+  bodyLength: 7.0
+  height: 0.85
+  leadWidth: 0.25
+  leadLength: 0.4
+  pitch: 0.5
+  leadCount: 48
+  tabWidth: 5.5
+  tabLength: 5.5
+  tabPosition: 0.0, 0.0
+
+housing@CxT: # LQFP48
+  suffix: CxT
+  pattern: QFP
+  bodyWidth: 7.0
+  bodyLength: 7.0
+  height: 1.5
+  leadWidth: 0.2
+  leadLength: 0.6
+  leadSpan: 9.0
+  pitch: 0.5
+  leadCount: 48
+  rowCount: 12
+  columnCount: 12