Memory-to-peripheral transfer in Embedded C - Step-by-Step Execution

Concept Flow - Memory-to-peripheral transfer

Start Transfer

↓

Read Data from Memory

↓

Check Peripheral Ready?

No→Wait

Yes↓

Write Data to Peripheral

↓

More Data?

Yes→Read Data from Memory

No↓

End Transfer

This flow shows reading data from memory, checking if the peripheral is ready, writing data to it, and repeating until all data is sent.

Execution Sample

Embedded C

uint8_t data[] = {10, 20, 30};
for (int i = 0; i < 3; i++) {
  while (!peripheral_ready());
  write_to_peripheral(data[i]);
}

This code sends three bytes from memory to a peripheral, waiting until the peripheral is ready before each write.

Execution Table

Step	i	Condition peripheral_ready()	Action	Data Sent
1	0	True	write_to_peripheral(10)	10
2	1	False	wait	10
3	1	True	write_to_peripheral(20)	20
4	2	True	write_to_peripheral(30)	30
5	3	N/A	End loop	All data sent

💡 i reaches 3, condition i < 3 is False, transfer ends

Variable Tracker

Variable	Start	After 1	After 2	After 3	Final
i	0	1	2	3	3
Data Sent	None	10	20	30	All data sent

Key Moments - 2 Insights

Why do we wait for peripheral_ready() before writing data?

Because the peripheral might not be ready to accept new data immediately. The execution_table rows 2 and 3 show waiting until peripheral_ready() returns True before sending the next byte.

What happens if we don't check peripheral readiness?

Data might be lost or corrupted because the peripheral can't handle new data yet. The loop in the code and the wait action in step 2 prevent this.

Visual Quiz - 3 Questions

Look at the execution_table, what data is sent at step 3?

A 10

B 20

C 30

D None

💡 Hint

Check the 'Data Sent' column at step 3 in the execution_table.

At which step does the peripheral_ready() condition return False?

A Step 4

B Step 1

C Step 2

D Step 5

💡 Hint

Look at the 'Condition peripheral_ready()' column in the execution_table.

If the data array had 4 elements instead of 3, how would the variable 'i' change in variable_tracker?

A It would go up to 4

B It would stay at 3

C It would go up to 5

D It would reset to 0

💡 Hint

The loop runs while i < length of data, so with 4 elements, i increments to 4.

Concept Snapshot

Memory-to-peripheral transfer in embedded C:
- Read data from memory array
- Wait until peripheral is ready
- Write data to peripheral
- Repeat until all data sent
- Prevents data loss by syncing with peripheral readiness

Full Transcript

This visual execution shows how data is transferred from memory to a peripheral device in embedded C. The program reads each byte from a memory array, waits until the peripheral signals it is ready, then writes the byte to the peripheral. This process repeats until all data is sent. The execution table tracks each step, showing the loop index, peripheral readiness check, action taken, and data sent. The variable tracker shows how the loop counter and data sent change over time. Key moments clarify why waiting for peripheral readiness is important to avoid data loss. The quiz tests understanding of the steps and variable changes. This step-by-step trace helps beginners see how memory-to-peripheral transfer works in real embedded code.