ECE 440 · Week 1
Modern Computer: Full Stack
A product requirement has three numbers or names: watts, seconds, and the person who applies an update.
Week 1 of 10 · Solitude
ECE 440 · Week 1
The board: Solitude
- 5 V
- 3.3 V
- Ground
- I2C
- SPI
- UART
- PWM
- TDM
- PDM
- Console TX
- Console RX
- Console ground
Colours as on the Solitude pinout, where each pin's name is. The square pad is pin 1.
ECE 440 · Week 1 · In class
A product requirement has three numbers or names: watts, seconds, and the person who applies an update.
- Watts is the power budget.
- Seconds is the boot-time limit.
- The person is who is allowed to apply an update, and who is allowed to raise the watt figure.
- The station is already booted.
ECE 440 · Week 1 · In class
A product requirement has three numbers or names: watts, seconds, and the person who applies an update. (continued)
- Bringing it up is not the hand-in.
ECE 440 · Week 1 · In class
You choose the figures in the lab.
- Read the page aloud to your partner and correct one missing unit.
- The homework converts your watt figure into milliwatts and names who may raise it.
- The lecture does not hand you a watt number to copy.
ECE 440 · Week 1 · Lecture
A requirement you can check
- A requirement is a sentence someone else can test and get the same answer.
- Each one carries a number and a unit, or a name: never "fast" or "low power".
- This product has three: a power budget, a boot-time limit, and who applies an update.
- Every later lab measures against this page, so a missing unit costs you all term.
ECE 440 · Week 1 · Lecture
Watts: the power budget
- Power is voltage times current:
P = V × I. Watts are joules per second. - Budget the input to the board, where the supply plugs in: that is what a product pays for.
- Say which state the budget covers: idle, busy, or the worst case.
- 1 W = 1000 mW. Write the unit every time you move a figure between pages.
ECE 440 · Week 1 · Lecture
Seconds: the boot-time limit
- A time needs a start event and an end event, both named.
- Start: power applied. End: the thing the user waits for, such as a login prompt or the service answering.
- "Boot time" with no end event is two different numbers in two notebooks.
- The limit is a ceiling the product must meet, not a measurement you already took.
ECE 440 · Week 1 · Lecture
Who applies an update
- Name a role, not a person: the role outlives the student who wrote the page.
- Say who may apply an update and who may raise the watt figure. They need not be the same role.
- A requirement nobody owns gets changed by whoever is in a hurry.
ECE 440 · Week 1 · Lecture
Common mistakes on the page
| Written | Problem |
|---|---|
| "Low power" | No number, no unit |
| A number with no unit | W or mW? s or ms? |
| "Boots in time" | No start or end event |
| "The admin updates it" | Who may raise the budget? |
Read the page aloud: a missing unit is easier to hear than to see.
ECE 440 · Week 1 · Lab
Lab
- On the booted station, write the product requirement: a power budget in watts, a boot-time limit in seconds, and who applies an update.
- Second pass: read the requirement aloud to your partner and correct one missing unit.
- Assemble the lab hand-in: A one-page requirement with the power budget, the boot-time limit, and who applies an update.
ECE 440 · Week 1 · Lab
Hand in
A one-page requirement with the power budget, the boot-time limit, and who applies an update.
ECE 440 · Week 1 · Homework
Homework
- Convert the watt figure you intend to use into milliwatts, and write who is allowed to raise that figure.
ECE 440 · Week 1 · Homework
Turn in
The milliwatt figure and the permission sentence.
ECE 440 · Week 1 · Read
Read
On the lab site: Module 12, A whole system, describes a product. This week grades that one-page requirement.
ECE 440 · Week 1 · Next
Week 2
A pinmux row has a pad, the function you claim, the function you must not claim, and an electrical limit.