UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 468

• Manufacturer Part Number: UPD78F0890GK(A)-GAJ-AX
• Description: 8BIT MCU, 128K FLASH, 7K RAM, LQFP
• Manufacturer: NEC

Specifications of UPD78F0890GK(A)-GAJ-AX

• Controller Family/series: UPD78F
• No. Of I/o's: 55
• Ram Memory Size: 7KB
• Cpu Speed: 20MHz
• No. Of Timers: 10
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 128KB
• Oscillator Type: External, Internal

16.10.2 Transmit history list function
from which data or remote frames have been were sent. The THL consists of storage elements equivalent to up to
seven messages, the last out-message pointer (LOPT) with the corresponding C0LOPT register, and the transmit
history list get pointer (TGPT) with the corresponding C0TGPT register.
operation modes.
By reading the C0LOPT register, therefore, the number of the message buffer that transmitted a data frame or remote
frame first can be checked. The LOPT pointer is utilized as a write pointer that indicates to what part of the THL a
message buffer number is recorded. Any time a data frame or remote frame is transmitted, the corresponding
message buffer number is recorded to the THL element indicated by the LOPT pointer. Each time recording to the
THL has been completed, the LOPT pointer is automatically incremented. In this way, the number of the message
buffer that has received and stored a frame will be recorded chronologically.
pointer indicates the first THL element that the CPU has not yet read. By reading the C0TGPT register by software,
the number of a message buffer that has completed transmission can be read. Each time a message buffer number
is read from the C0TGPT register, the TGPT pointer is automatically incremented.
match) of the C0TGPT register is set to 1. This indicates that no message buffer numbers that have not been read
remain in the THL. If a new message buffer number is recorded, the LOPT pointer is incremented and because its
value no longer matches the value of the TGPT pointer, the THPM bit is cleared. In other words, the numbers of the
unread message buffers exist in the THL.
history list overflow) of the C0TGPT register is set to 1. This indicates that the THL is full of message buffer numbers
that have not been read. If a new message is received and stored, the message buffer number recorded last is
overwritten by the number of the message buffer that transmitted its message afterwards. After the TOVF bit has
been set (1), therefore, the recorded message buffer numbers in the THL do not completely reflect the chronological
order. However the other transmitted messages can be found by a CPU search applied to all transmit message
buffers unless the CPU has not overwritten a transmit object in one of these buffers beforehand. In total up to six
transmission completions can occur without overflowing the THL.
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The transmit history list (THL) function records in the transmit history list the number of the transmit message buffer
The THL is undefined immediately after the transition of the CAN module from the initialization mode to one of the
The C0LOPT register holds the contents of the THL element indicated by the value of the LOPT pointer minus 1.
The TGPT pointer is utilized as a read pointer that reads a recorded message buffer number from the THL. This
If the value of the TGPT pointer matches the value of the LOPT pointer, the THPM bit (transmit history list pointer
If the LOPT pointer is incremented and matches the value of the TGPT pointer minus 1, the TOVF bit (transmit
Caution
Remark
If the history list is in the overflow condition (TOVF is set), reading the history list contents is
still possible, until the history list is empty (indicated by THPM flag set). Nevertheless, the
history list remains in the overflow condition, until TOVF is cleared by software. If TOVF is not
cleared, the THPM flag will also not be updated (cleared) upon successful transmission of a
new message. This may lead to the situation, that THPM indicates an empty history list,
although a successful transmission has taken place, while the history list is in the overflow
state (TOVF and THPM are set).
m = 0 to 15
CHAPTER 16 CAN CONTROLLER
User’s Manual U17554EJ4V0UD