RFM119W Datasheet, PDF (15/19 Pages) List of Unclassifed Manufacturers – Low-Cost Consumer Electronics Applications

W
Parameter
Digital Input Level High
Digital Input Level Low
CLK Frequency
CLK High Time
CLK Low Time
CLK Delay Time
DATA Delay Time
DATA Setup Time
DATA Hold Time
RFM119W/RFM119SW
Table 12. TWI Requirements
Symbol
Conditions
Min Typ Max Unit
V_IH
0.8
V_IL
F_CLK
10
t_CH
500
t_CL
500
CLK delay time for the first falling edge of the
t_CD
TWI_RST command, see Figure 20
20
The data delay time from the last CLK rising
t_DD edge of the TWI command to the time DATA
return to default state
t_DS
From DATA change to CLK falling edge
20
t_DH From CLK falling edge to DATA change
200
V_DD
0.2
V_DD
1,000 kHz
ns
ns
15,000 ns
15,000 ns
ns
ns
CLK
tCH tCL
tDS tDH
DATA
Figure 18. Two-wire Interface Timing Diagram
Once the device is powered up, TWI_RST and SOFT_RST should be issued to make sure the device works in SLEEP state
robustly. On every transmission, TWI_RST and TWI_OFF should be issued before the transmission to make sure the TWI
circuit functions correctly. TWI_RST and SOFT_RST should be issued again after the transmission for the device going back to
SLEEP state reliably till the next transmission. The operation flow with TWI is shown as the figure below.
Reset TWI
One Transmission Cycle
One Transmission Cycle
(1) ‐ TWI_RST
(2) ‐ SOFT_RST
(1) ‐ TWI_RST
(2) ‐ TWI_OFF
TRANSMISSION
(1) ‐ TWI_RST
(2) ‐ SOFT_RST
(1) ‐ TWI_RST
(2) ‐ TWI_OFF
TRANSMISSION
Figure 19. RFM119W/S Operation Flow with
TWI
(1) ‐ TWI_RST
(2) ‐ SOFT_RST
Table 13. TWI Commands Descriptions
Command
Descriptions
Implemented by pulling the DATA pin low for 32 clock cycles and clocking in 0x8D00, 48 clock cycles in total.
TWI_RST
It only resets the TWI circuit to make sure it functions correctly. The DATA pin cannot detect the
Rising/Falling edge to trigger transmission after this command, until the TWI_OFF command is issued.
Notes:
1. Please ensure the DATA pin is firmly pulled low during the first 32 clock cycles.
2. When the device is configured as Transmission Enabled by DATA Pin Falling Edge, in order to issue
the TWI_RST command correctly, the first falling edge of the CLK should be sent t_CD after the DATA
falling edge, which should be longer than the minimum DATA setup time 20 ns, and shorter than 15 us,
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