User Manual

MGC3030/3130
DS40001667E-page 32 Advance Information  2012-2017 Microchip Technology Inc.
MGC3X30 can update the I
2
C buffer only when the TS
is released by both chips and a data transfer can only
be started when MGC3X30 pulls the TS low.
This procedure secures that:
• the host is always informed when new sensor
data is available
• buffer updates in MGC3X30 are always
completed before data is sent to the I
2
C bus
Figure 5-3 shows the complete communication
protocol.
FIGURE 5-3: MGC3X30 COMMUNICATION PROTOCOL
In addition to the standard I
2
C interface, the
communication between MGC3X30 and the host
controller requires a proper handling of the Transfer
Status.
TABLE 5-9: USAGE OF TRANSFER STATUS LINE
MGC3X30 Host Controller TS Line Status
Released (H) Released (H) High Host finished reading data (Transfer end). No more data to
be transferred to the host. MGC3X30 is allowed to update the
data buffer.
Asserted (L) Released (H) Low Data from MGC3X30 is available to be sent, but the host has
not yet started reading. If the host is busy and did not start
reading before the next data update (5 ms), the MGC3X30
will assert the TS line high while updating the data buffer.
Asserted (L) Asserted (L) Low Host starts reading. MGC3X30 data buffer will not be
updated until the end of transfer (host releases TS high).
Released (H) Asserted (L) Low MGC3X30 is ready to update the data buffer, but the host is
still reading the previous data. MGC3X30 is allowed to
update the data only when the host releases the TS high.
Transfer Status
(TS)
I
2
C
TM
Bus
MGC3130 Related Transfer MGC3130 Related Transfer
TS line pulled
low by master
when transfer
is started
TS line released
by master and
MGC3130 when
transfer is
finished
TS line pulled
by MGC3130
to request a
data transfer
MGC3130 buffer
can be updated
Non MGC3130 related transfer or Bus Idle
TS line pulled
low by master
when transfer is
started
MGC3130 buffer
can be updated
TS line pulled
by MGC3130
to request a
data transfer
TS line released
by master and
MGC3130 when
transfer is
finished
Note 1: The stop condition after an I
2
C™ data
transmission is generated by the host
controller (I
2
C™ Master) after the data
transfer is completed. Thus, it is
recommended to verify the amount of
bytes to be read in the message header
(Size field).
2: Transfer Status is only needed for data
transfer from MGC3X30 to the host
controller. Writing to MGC3X30 does not
require the additional TS signal.